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Bullying in Schools: Causes, Effects, and Solutions

• Categories: Bullying Youth Violence

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Published: Dec 16, 2021

Words: 1534 | Pages: 3 | 8 min read

Works Cited

• Bradshaw, C. P., Sawyer, A. L., & O'Brennan, L. M. (2007). Bullying and peer victimization at school: Perceptual differences between students and school staff. School Psychology Review, 36(3), 361-382.
• Espelage, D. L., & Swearer, S. M. (2003). Research on school bullying and victimization: What have we learned and where do we go from here?. School Psychology Review, 32(3), 365-383.
• Hinduja, S., & Patchin, J. W. (2018). Cyberbullying fact sheet: Identification, prevention, and response. Cyberbullying Research Center.
• National Bullying Prevention Center. (2021). Resources. https://www.pacer.org/bullying/resources/
• National Center for Education Statistics. (2022). Student reports of bullying and cyberbullying: Results from the 2020–21 School Crime Supplement to the National Crime Victimization Survey. US Department of Education.
• Olweus, D. (2013). School bullying: Development and some important challenges. Annual Review of Clinical Psychology, 9, 751-780.
• Patchin, J. W., & Hinduja, S. (2020). School climate 2.0: Preventing cyberbullying and sexting one classroom at a time. Corwin Press.
• StopBullying.gov. (2021). Prevent bullying. https://www.stopbullying.gov/prevention/index.html
• Thompson, F., Smith, P. K., & Rigby, K. (2022). Addressing bullying in schools: Theory and practice. Routledge.
• Ttofi, M. M., & Farrington, D. P. (2011). Effectiveness of school-based programs to reduce bullying: A systematic and meta-analytic review. Journal of Experimental Criminology, 7(1), 27-56.

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School Bullying: Causes and Effects

Bullying has become one of the most urgent problems in modern society. It comes from different sources and affects victims’ psychological state and quality of life. In this essay, we analyze the causes of bullying in school, its effects on victims, and mitigation measures that should be taken.

Cause and Effect of Bullying: Essay Introduction

Cause of bullying in school, bullying causes and effects: mitigation measures, works cited.

Bullying is one of the main challenges children face at school. It is a global problem that is currently affecting many youth. The rate at which bullying cases are reported causes many worries to parents. The issue is severe to the extent that many children have learned to live with it, and some have created the notion that bullying is part of their life in the early years of their development. Several cases, especially in the United States and Japan, have been reported about children’s humiliation, mistreatment, physical attacks, and even rape cases of young female learners.

The effects of bullying on a child can be very traumatizing if not carefully addressed. These effects sometimes are long-lasting and can provoke the victim to take dangerous measures to forget the incidents. According to Rigby (64), bullying experiences can cost the lives of the victims if not prevented in time. In New York, it is reported that a young immigrant killed herself due to excessive bullying. This researcher argues that it is high time for the issue of bullying in schools to be addressed. The notion that bullying is a rite of passage should be eliminated. This research paper aims to explore the causes, effects, and possible solutions to bullying in schools.

According to Olweus (34), many reasons lead to bullying in schools. One of the main causes is the cultural factor. This includes race and ethnicity. A child may be a bully or a victim if he or she comes from a majority or minority race, respectively. Another cause of bullying in schools is the nature of life a child is exposed to. In many families in developed countries, children can comfortably watch TV even in their bedrooms. Instead of studying, such children spend their time playing computer games. Their games make them bullies because they see others practice the same.

According to Tattumand Lane (27), high expectations of parents of their children contribute to bullying. The reason is that a child will spend much time studying to perform well and meet the parents’ expectations. Failure to achieve the target may develop stress in a child, and they will express anger through shouting or bullying fellow learners. Another cause of bullying in schools emanates from the family’s social status. A child from a humble background will always have some pressurizing needs that are not met. This child will always want to express this frustration to fellow learners, especially those from stable families, by bullying them.

The effects of bullying, as mentioned above, can be very traumatizing. Victims of bullying may opt to drop out of school because of the trauma they experience. Others may develop irresponsible behavior that involves missing classes on most occasions. School irregularities among the learners result in poor performance. Bullying leads to stress among the victims. This, in turn, results in poor communication with these children. McGrath (44) argues that, in some cases, excessive bullying can lead to victims committing suicide to escape from painful experiences and memories.

Some of the effects are short-term, but if not well addressed, they can result in serious complications. The victims may have bed-wetting problems, unexplained worries, and digestive problems because of the fear instilled in them. Some victims with the intention of hitting back may develop very destructive behavior. Other victims may end up engaging in drug abuse to make them forget their painful experiences. Bullying affects the normal development of victims and makes them have low self-esteem (Dupper 62). 

Mitigating bullying in schools is not a one-person battle. Since it is a global issue, it calls for a collaborative and participatory approach to addressing the problem. Teachers, parents, and policymakers have a significant role in curbing this bad behavior in schools. Teachers spend much of their time with the learners and, therefore, can easily control their behavior while in school. They should be tough and keen to identify the bullies and expel or suspend them from school to avoid spreading such behaviors among other learners. School administrators should seriously punish the physically strong learners who take advantage of the weak ones by mistreating them. The administration should not tolerate any sign of bullying within the school (Tattum&Lane 53). 

Parents should also be strict with their children and avoid anything that may turn them into bullies. Watching TV and playing computer games must be regulated at home. The child should be seriously punished if he or she shows some bullying behavior while at home. The government also has an essential role in curbing this vice. Policymakers must enact policies that address bullying in schools. These policies should be implemented and strictly adhered to, and whoever violates them should face the law irrespective of age. All the stakeholders, including the humanitarian non-governmental organizations, must join hands to curb this vice in society. Through this collaborative approach, success will be achieved.

Dupper, David. School Bullying: New Perspectives on a Growing Problem . New York: Oxford University Press, 2013. Print.

McGrath, Mary. School Bullying: Tools for Avoiding Harm and Liability . Thousand Oaks, Calif: Corwin Press, 2007. Print.

Olweus, Dan. Bullying at School: What We Know and What We Can Do . Oxford, UK: Blackwell, 1993. Print.

Rigby, Ken. Bullying in Schools and What to Do About It . Melbourne, Vic: ACER, 2007. Print.

Tattum, Delwyn, and David Lane. Bullying in Schools . Stoke-on-Trent: Trentham, 1988. Print.

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Defining school bullying and its implications on education, teachers and learners

Contributing to UNESCO’s work on fostering safe learning environments , which addresses many different forms of violence, the UNESCO Chair on Bullying and Cyberbullying, in collaboration with the World Anti-Bullying Forum (WABF), led an international working group to create a more holistic and inclusive definition of school bullying. Professor James O’Higgins Norman, UNESCO Chair on Bullying and Cyberbullying, shares his insights on this work.

Why revisit the definition of bullying?

Many current anti-bullying programmes in schools are rooted in early definitions characterizing bullying as an “unwanted aggressive behavior that is repeated over time and involves an imbalance of power or strength”. While this was groundbreaking at the time and advanced the work of researchers, policy makers, educators and others, evolving perspectives have deepened our understanding of bullying.

Research shows that progress in reducing school bullying has been slow, with only a 19% decrease in perpetration and a 15% drop in the rate of learners facing bullying. This means we must reassess our understanding and approaches to bullying, especially in our increasingly complex world, where both in-person and online bullying intertwine with personal and societal issues.

How are you revisiting the definition of bullying?

As a UNESCO Chair, my role involves facilitating interdisciplinary research and dialogue, and working towards a more holistic approach to bullying. Our recommendation for a ‘whole-education’ approach to tackle bullying recognizes individual, contextual, and societal dimensions.

With support from UNESCO and the WABF, I facilitated the working group to revisit the definition of bullying, consulting scholars, policymakers and practitioners worldwide. We gathered feedback from a diverse group and have conducted wide consultations. This working group was launched following the recommendations by a Scientific Committee on preventing and addressing school bullying and cyberbullying, convened by UNESCO and the French Ministry of Education, Youth and Sports.

What would a revised definition mean for education policymakers and practitioners, for school communities and learners?

The proposed definition promotes a holistic and inclusion-driven approach to tackling bullying and violence in schools and in online spaces. 

Crafting a more inclusive definition has the potential to break down academic and professional barriers, encouraging cooperation between sectors, and among scholars, policymakers, educators, and learners. It provides a solid foundation to better understand bullying particularly regarding those most marginalized due to appearance, ethnicity, gender, social class, or sexuality, among others. Bullying is a complex issue tied to individual, contextual, and structural factors, making collaboration essential.

Together, we can deepen our understanding and address not only the behavior but also the underlying systems and ideologies supporting bullying.

What is your vision for this improved definition of school bullying?

My vision aligns with United Nations Sustainable Development Goal 4, on education, in that our work on bullying, and all other forms of school violence, is aimed at ensuring an inclusive and equitable quality education and the promotion of lifelong learning opportunities for all. 

What message do you have for teachers and learners?

To teachers and school staff: Do not accept bullying as normal. Create a safe classroom environment by setting clear expectations for kindness and respect, remain vigilant for signs of bullying, stay informed about effective prevention strategies, and promptly address any incidents. Implement a robust anti-bullying policy. Under the idea of a ‘whole-education’ approach, collaborate with colleagues and parents, incorporate empathy and anti-bullying content into the curriculum, and use collaborative learning methods.

To learners: Report bullying, be confident in recognizing and responding to it, and encourage bystander intervention. You have the power to stop bullying.

New definition and what’s next?

The working group presented its proposed revised definition of school bullying at the WABF held in October 2023. The proposed definition reads:

School bullying is a damaging social process that is characterized by an imbalance of power driven by social (societal) and institutional norms. It is often repeated and manifests as unwanted interpersonal behaviour among students or school personnel that causes physical, social, and emotional harm to the targeted individuals or groups, and the wider school community.

This new inclusive definition of school bullying was largely welcomed by delegates at the Forum. The UNESCO Chair and WABF hope that this revised definition will contribute to opening a new chapter in the global conversation on the nature of and responses to bullying and cyberbullying. 

For UNESCO, the new definition of bullying reflects our approach and work to ensure that schools are safe and supportive learning environments. This means that to end all forms of school violence, including bullying, we must understand that these behaviours do not happen in isolation, that there are different drivers of violence, and that a ‘whole-education’ approach is needed. 

More information

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• International Day Against Violence and Bullying at School, including Cyberbullying
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• Research article
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• Published: 14 December 2021

Bullying at school and mental health problems among adolescents: a repeated cross-sectional study

• Håkan Källmén 1 &
• Mats Hallgren   ORCID: orcid.org/0000-0002-0599-2403 2  

Child and Adolescent Psychiatry and Mental Health volume  15 , Article number:  74 ( 2021 ) Cite this article

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To examine recent trends in bullying and mental health problems among adolescents and the association between them.

A questionnaire measuring mental health problems, bullying at school, socio-economic status, and the school environment was distributed to all secondary school students aged 15 (school-year 9) and 18 (school-year 11) in Stockholm during 2014, 2018, and 2020 (n = 32,722). Associations between bullying and mental health problems were assessed using logistic regression analyses adjusting for relevant demographic, socio-economic, and school-related factors.

The prevalence of bullying remained stable and was highest among girls in year 9; range = 4.9% to 16.9%. Mental health problems increased; range = + 1.2% (year 9 boys) to + 4.6% (year 11 girls) and were consistently higher among girls (17.2% in year 11, 2020). In adjusted models, having been bullied was detrimentally associated with mental health (OR = 2.57 [2.24–2.96]). Reports of mental health problems were four times higher among boys who had been bullied compared to those not bullied. The corresponding figure for girls was 2.4 times higher.

Conclusions

Exposure to bullying at school was associated with higher odds of mental health problems. Boys appear to be more vulnerable to the deleterious effects of bullying than girls.

Introduction

Bullying involves repeated hurtful actions between peers where an imbalance of power exists [ 1 ]. Arseneault et al. [ 2 ] conducted a review of the mental health consequences of bullying for children and adolescents and found that bullying is associated with severe symptoms of mental health problems, including self-harm and suicidality. Bullying was shown to have detrimental effects that persist into late adolescence and contribute independently to mental health problems. Updated reviews have presented evidence indicating that bullying is causative of mental illness in many adolescents [ 3 , 4 ].

There are indications that mental health problems are increasing among adolescents in some Nordic countries. Hagquist et al. [ 5 ] examined trends in mental health among Scandinavian adolescents (n = 116, 531) aged 11–15 years between 1993 and 2014. Mental health problems were operationalized as difficulty concentrating, sleep disorders, headache, stomach pain, feeling tense, sad and/or dizzy. The study revealed increasing rates of adolescent mental health problems in all four counties (Finland, Sweden, Norway, and Denmark), with Sweden experiencing the sharpest increase among older adolescents, particularly girls. Worsening adolescent mental health has also been reported in the United Kingdom. A study of 28,100 school-aged adolescents in England found that two out of five young people scored above thresholds for emotional problems, conduct problems or hyperactivity [ 6 ]. Female gender, deprivation, high needs status (educational/social), ethnic background, and older age were all associated with higher odds of experiencing mental health difficulties.

Bullying is shown to increase the risk of poor mental health and may partly explain these detrimental changes. Le et al. [ 7 ] reported an inverse association between bullying and mental health among 11–16-year-olds in Vietnam. They also found that poor mental health can make some children and adolescents more vulnerable to bullying at school. Bayer et al. [ 8 ] examined links between bullying at school and mental health among 8–9-year-old children in Australia. Those who experienced bullying more than once a week had poorer mental health than children who experienced bullying less frequently. Friendships moderated this association, such that children with more friends experienced fewer mental health problems (protective effect). Hysing et al. [ 9 ] investigated the association between experiences of bullying (as a victim or perpetrator) and mental health, sleep disorders, and school performance among 16–19 year olds from Norway (n = 10,200). Participants were categorized as victims, bullies, or bully-victims (that is, victims who also bullied others). All three categories were associated with worse mental health, school performance, and sleeping difficulties. Those who had been bullied also reported more emotional problems, while those who bullied others reported more conduct disorders [ 9 ].

As most adolescents spend a considerable amount of time at school, the school environment has been a major focus of mental health research [ 10 , 11 ]. In a recent review, Saminathen et al. [ 12 ] concluded that school is a potential protective factor against mental health problems, as it provides a socially supportive context and prepares students for higher education and employment. However, it may also be the primary setting for protracted bullying and stress [ 13 ]. Another factor associated with adolescent mental health is parental socio-economic status (SES) [ 14 ]. A systematic review indicated that lower parental SES is associated with poorer adolescent mental health [ 15 ]. However, no previous studies have examined whether SES modifies or attenuates the association between bullying and mental health. Similarly, it remains unclear whether school related factors, such as school grades and the school environment, influence the relationship between bullying and mental health. This information could help to identify those adolescents most at risk of harm from bullying.

To address these issues, we investigated the prevalence of bullying at school and mental health problems among Swedish adolescents aged 15–18 years between 2014 and 2020 using a population-based school survey. We also examined associations between bullying at school and mental health problems adjusting for relevant demographic, socioeconomic, and school-related factors. We hypothesized that: (1) bullying and adolescent mental health problems have increased over time; (2) There is an association between bullying victimization and mental health, so that mental health problems are more prevalent among those who have been victims of bullying; and (3) that school-related factors would attenuate the association between bullying and mental health.

Participants

The Stockholm school survey is completed every other year by students in lower secondary school (year 9—compulsory) and upper secondary school (year 11). The survey is mandatory for public schools, but voluntary for private schools. The purpose of the survey is to help inform decision making by local authorities that will ultimately improve students’ wellbeing. The questions relate to life circumstances, including SES, schoolwork, bullying, drug use, health, and crime. Non-completers are those who were absent from school when the survey was completed (< 5%). Response rates vary from year to year but are typically around 75%. For the current study data were available for 2014, 2018 and 2020. In 2014; 5235 boys and 5761 girls responded, in 2018; 5017 boys and 5211 girls responded, and in 2020; 5633 boys and 5865 girls responded (total n = 32,722). Data for the exposure variable, bullied at school, were missing for 4159 students, leaving 28,563 participants in the crude model. The fully adjusted model (described below) included 15,985 participants. The mean age in grade 9 was 15.3 years (SD = 0.51) and in grade 11, 17.3 years (SD = 0.61). As the data are completely anonymous, the study was exempt from ethical approval according to an earlier decision from the Ethical Review Board in Stockholm (2010-241 31-5). Details of the survey are available via a website [ 16 ], and are described in a previous paper [ 17 ].

Students completed the questionnaire during a school lesson, placed it in a sealed envelope and handed it to their teacher. Student were permitted the entire lesson (about 40 min) to complete the questionnaire and were informed that participation was voluntary (and that they were free to cancel their participation at any time without consequences). Students were also informed that the Origo Group was responsible for collection of the data on behalf of the City of Stockholm.

Study outcome

Mental health problems were assessed by using a modified version of the Psychosomatic Problem Scale [ 18 ] shown to be appropriate for children and adolescents and invariant across gender and years. The scale was later modified [ 19 ]. In the modified version, items about difficulty concentrating and feeling giddy were deleted and an item about ‘life being great to live’ was added. Seven different symptoms or problems, such as headaches, depression, feeling fear, stomach problems, difficulty sleeping, believing it’s great to live (coded negatively as seldom or rarely) and poor appetite were used. Students who responded (on a 5-point scale) that any of these problems typically occurs ‘at least once a week’ were considered as having indicators of a mental health problem. Cronbach alpha was 0.69 across the whole sample. Adding these problem areas, a total index was created from 0 to 7 mental health symptoms. Those who scored between 0 and 4 points on the total symptoms index were considered to have a low indication of mental health problems (coded as 0); those who scored between 5 and 7 symptoms were considered as likely having mental health problems (coded as 1).

Primary exposure

Experiences of bullying were measured by the following two questions: Have you felt bullied or harassed during the past school year? Have you been involved in bullying or harassing other students during this school year? Alternatives for the first question were: yes or no with several options describing how the bullying had taken place (if yes). Alternatives indicating emotional bullying were feelings of being mocked, ridiculed, socially excluded, or teased. Alternatives indicating physical bullying were being beaten, kicked, forced to do something against their will, robbed, or locked away somewhere. The response alternatives for the second question gave an estimation of how often the respondent had participated in bullying others (from once to several times a week). Combining the answers to these two questions, five different categories of bullying were identified: (1) never been bullied and never bully others; (2) victims of emotional (verbal) bullying who have never bullied others; (3) victims of physical bullying who have never bullied others; (4) victims of bullying who have also bullied others; and (5) perpetrators of bullying, but not victims. As the number of positive cases in the last three categories was low (range = 3–15 cases) bully categories 2–4 were combined into one primary exposure variable: ‘bullied at school’.

Assessment year was operationalized as the year when data was collected: 2014, 2018, and 2020. Age was operationalized as school grade 9 (15–16 years) or 11 (17–18 years). Gender was self-reported (boy or girl). The school situation To assess experiences of the school situation, students responded to 18 statements about well-being in school, participation in important school matters, perceptions of their teachers, and teaching quality. Responses were given on a four-point Likert scale ranging from ‘do not agree at all’ to ‘fully agree’. To reduce the 18-items down to their essential factors, we performed a principal axis factor analysis. Results showed that the 18 statements formed five factors which, according to the Kaiser criterion (eigen values > 1) explained 56% of the covariance in the student’s experience of the school situation. The five factors identified were: (1) Participation in school; (2) Interesting and meaningful work; (3) Feeling well at school; (4) Structured school lessons; and (5) Praise for achievements. For each factor, an index was created that was dichotomised (poor versus good circumstance) using the median-split and dummy coded with ‘good circumstance’ as reference. A description of the items included in each factor is available as Additional file 1 . Socio-economic status (SES) was assessed with three questions about the education level of the student’s mother and father (dichotomized as university degree versus not), and the amount of spending money the student typically received for entertainment each month (> SEK 1000 [approximately $120] versus less). Higher parental education and more spending money were used as reference categories. School grades in Swedish, English, and mathematics were measured separately on a 7-point scale and dichotomized as high (grades A, B, and C) versus low (grades D, E, and F). High school grades were used as the reference category.

Statistical analyses

The prevalence of mental health problems and bullying at school are presented using descriptive statistics, stratified by survey year (2014, 2018, 2020), gender, and school year (9 versus 11). As noted, we reduced the 18-item questionnaire assessing school function down to five essential factors by conducting a principal axis factor analysis (see Additional file 1 ). We then calculated the association between bullying at school (defined above) and mental health problems using multivariable logistic regression. Results are presented as odds ratios (OR) with 95% confidence intervals (Cis). To assess the contribution of SES and school-related factors to this association, three models are presented: Crude, Model 1 adjusted for demographic factors: age, gender, and assessment year; Model 2 adjusted for Model 1 plus SES (parental education and student spending money), and Model 3 adjusted for Model 2 plus school-related factors (school grades and the five factors identified in the principal factor analysis). These covariates were entered into the regression models in three blocks, where the final model represents the fully adjusted analyses. In all models, the category ‘not bullied at school’ was used as the reference. Pseudo R-square was calculated to estimate what proportion of the variance in mental health problems was explained by each model. Unlike the R-square statistic derived from linear regression, the Pseudo R-square statistic derived from logistic regression gives an indicator of the explained variance, as opposed to an exact estimate, and is considered informative in identifying the relative contribution of each model to the outcome [ 20 ]. All analyses were performed using SPSS v. 26.0.

Prevalence of bullying at school and mental health problems

Estimates of the prevalence of bullying at school and mental health problems across the 12 strata of data (3 years × 2 school grades × 2 genders) are shown in Table 1 . The prevalence of bullying at school increased minimally (< 1%) between 2014 and 2020, except among girls in grade 11 (2.5% increase). Mental health problems increased between 2014 and 2020 (range = 1.2% [boys in year 11] to 4.6% [girls in year 11]); were three to four times more prevalent among girls (range = 11.6% to 17.2%) compared to boys (range = 2.6% to 4.9%); and were more prevalent among older adolescents compared to younger adolescents (range = 1% to 3.1% higher). Pooling all data, reports of mental health problems were four times more prevalent among boys who had been victims of bullying compared to those who reported no experiences with bullying. The corresponding figure for girls was two and a half times as prevalent.

Associations between bullying at school and mental health problems

Table 2 shows the association between bullying at school and mental health problems after adjustment for relevant covariates. Demographic factors, including female gender (OR = 3.87; CI 3.48–4.29), older age (OR = 1.38, CI 1.26–1.50), and more recent assessment year (OR = 1.18, CI 1.13–1.25) were associated with higher odds of mental health problems. In Model 2, none of the included SES variables (parental education and student spending money) were associated with mental health problems. In Model 3 (fully adjusted), the following school-related factors were associated with higher odds of mental health problems: lower grades in Swedish (OR = 1.42, CI 1.22–1.67); uninteresting or meaningless schoolwork (OR = 2.44, CI 2.13–2.78); feeling unwell at school (OR = 1.64, CI 1.34–1.85); unstructured school lessons (OR = 1.31, CI = 1.16–1.47); and no praise for achievements (OR = 1.19, CI 1.06–1.34). After adjustment for all covariates, being bullied at school remained associated with higher odds of mental health problems (OR = 2.57; CI 2.24–2.96). Demographic and school-related factors explained 12% and 6% of the variance in mental health problems, respectively (Pseudo R-Square). The inclusion of socioeconomic factors did not alter the variance explained.

Our findings indicate that mental health problems increased among Swedish adolescents between 2014 and 2020, while the prevalence of bullying at school remained stable (< 1% increase), except among girls in year 11, where the prevalence increased by 2.5%. As previously reported [ 5 , 6 ], mental health problems were more common among girls and older adolescents. These findings align with previous studies showing that adolescents who are bullied at school are more likely to experience mental health problems compared to those who are not bullied [ 3 , 4 , 9 ]. This detrimental relationship was observed after adjustment for school-related factors shown to be associated with adolescent mental health [ 10 ].

A novel finding was that boys who had been bullied at school reported a four-times higher prevalence of mental health problems compared to non-bullied boys. The corresponding figure for girls was 2.5 times higher for those who were bullied compared to non-bullied girls, which could indicate that boys are more vulnerable to the deleterious effects of bullying than girls. Alternatively, it may indicate that boys are (on average) bullied more frequently or more intensely than girls, leading to worse mental health. Social support could also play a role; adolescent girls often have stronger social networks than boys and could be more inclined to voice concerns about bullying to significant others, who in turn may offer supports which are protective [ 21 ]. Related studies partly confirm this speculative explanation. An Estonian study involving 2048 children and adolescents aged 10–16 years found that, compared to girls, boys who had been bullied were more likely to report severe distress, measured by poor mental health and feelings of hopelessness [ 22 ].

Other studies suggest that heritable traits, such as the tendency to internalize problems and having low self-esteem are associated with being a bully-victim [ 23 ]. Genetics are understood to explain a large proportion of bullying-related behaviors among adolescents. A study from the Netherlands involving 8215 primary school children found that genetics explained approximately 65% of the risk of being a bully-victim [ 24 ]. This proportion was similar for boys and girls. Higher than average body mass index (BMI) is another recognized risk factor [ 25 ]. A recent Australian trial involving 13 schools and 1087 students (mean age = 13 years) targeted adolescents with high-risk personality traits (hopelessness, anxiety sensitivity, impulsivity, sensation seeking) to reduce bullying at school; both as victims and perpetrators [ 26 ]. There was no significant intervention effect for bullying victimization or perpetration in the total sample. In a secondary analysis, compared to the control schools, intervention school students showed greater reductions in victimization, suicidal ideation, and emotional symptoms. These findings potentially support targeting high-risk personality traits in bullying prevention [ 26 ].

The relative stability of bullying at school between 2014 and 2020 suggests that other factors may better explain the increase in mental health problems seen here. Many factors could be contributing to these changes, including the increasingly competitive labour market, higher demands for education, and the rapid expansion of social media [ 19 , 27 , 28 ]. A recent Swedish study involving 29,199 students aged between 11 and 16 years found that the effects of school stress on psychosomatic symptoms have become stronger over time (1993–2017) and have increased more among girls than among boys [ 10 ]. Research is needed examining possible gender differences in perceived school stress and how these differences moderate associations between bullying and mental health.

Strengths and limitations

Strengths of the current study include the large participant sample from diverse schools; public and private, theoretical and practical orientations. The survey included items measuring diverse aspects of the school environment; factors previously linked to adolescent mental health but rarely included as covariates in studies of bullying and mental health. Some limitations are also acknowledged. These data are cross-sectional which means that the direction of the associations cannot be determined. Moreover, all the variables measured were self-reported. Previous studies indicate that students tend to under-report bullying and mental health problems [ 29 ]; thus, our results may underestimate the prevalence of these behaviors.

In conclusion, consistent with our stated hypotheses, we observed an increase in self-reported mental health problems among Swedish adolescents, and a detrimental association between bullying at school and mental health problems. Although bullying at school does not appear to be the primary explanation for these changes, bullying was detrimentally associated with mental health after adjustment for relevant demographic, socio-economic, and school-related factors, confirming our third hypothesis. The finding that boys are potentially more vulnerable than girls to the deleterious effects of bullying should be replicated in future studies, and the mechanisms investigated. Future studies should examine the longitudinal association between bullying and mental health, including which factors mediate/moderate this relationship. Epigenetic studies are also required to better understand the complex interaction between environmental and biological risk factors for adolescent mental health [ 24 ].

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Olweus D. School bullying: development and some important challenges. Ann Rev Clin Psychol. 2013;9(9):751–80. https://doi.org/10.1146/annurev-clinpsy-050212-185516 .

Article   Google Scholar  

Arseneault L, Bowes L, Shakoor S. Bullying victimization in youths and mental health problems: “Much ado about nothing”? Psychol Med. 2010;40(5):717–29. https://doi.org/10.1017/S0033291709991383 .

Article   CAS   PubMed   Google Scholar  

Arseneault L. The long-term impact of bullying victimization on mental health. World Psychiatry. 2017;16(1):27–8. https://doi.org/10.1002/wps.20399 .

Article   PubMed   PubMed Central   Google Scholar  

Moore SE, Norman RE, Suetani S, Thomas HJ, Sly PD, Scott JG. Consequences of bullying victimization in childhood and adolescence: a systematic review and meta-analysis. World J Psychiatry. 2017;7(1):60–76. https://doi.org/10.5498/wjp.v7.i1.60 .

Hagquist C, Due P, Torsheim T, Valimaa R. Cross-country comparisons of trends in adolescent psychosomatic symptoms—a Rasch analysis of HBSC data from four Nordic countries. Health Qual Life Outcomes. 2019;17(1):27. https://doi.org/10.1186/s12955-019-1097-x .

Deighton J, Lereya ST, Casey P, Patalay P, Humphrey N, Wolpert M. Prevalence of mental health problems in schools: poverty and other risk factors among 28 000 adolescents in England. Br J Psychiatry. 2019;215(3):565–7. https://doi.org/10.1192/bjp.2019.19 .

Article   PubMed Central   Google Scholar  

Le HTH, Tran N, Campbell MA, Gatton ML, Nguyen HT, Dunne MP. Mental health problems both precede and follow bullying among adolescents and the effects differ by gender: a cross-lagged panel analysis of school-based longitudinal data in Vietnam. Int J Ment Health Syst. 2019. https://doi.org/10.1186/s13033-019-0291-x .

Bayer JK, Mundy L, Stokes I, Hearps S, Allen N, Patton G. Bullying, mental health and friendship in Australian primary school children. Child Adolesc Ment Health. 2018;23(4):334–40. https://doi.org/10.1111/camh.12261 .

Article   PubMed   Google Scholar  

Hysing M, Askeland KG, La Greca AM, Solberg ME, Breivik K, Sivertsen B. Bullying involvement in adolescence: implications for sleep, mental health, and academic outcomes. J Interpers Violence. 2019. https://doi.org/10.1177/0886260519853409 .

Hogberg B, Strandh M, Hagquist C. Gender and secular trends in adolescent mental health over 24 years—the role of school-related stress. Soc Sci Med. 2020. https://doi.org/10.1016/j.socscimed.2020.112890 .

Kidger J, Araya R, Donovan J, Gunnell D. The effect of the school environment on the emotional health of adolescents: a systematic review. Pediatrics. 2012;129(5):925–49. https://doi.org/10.1542/peds.2011-2248 .

Saminathen MG, Låftman SB, Modin B. En fungerande skola för alla: skolmiljön som skyddsfaktor för ungas psykiska välbefinnande. [A functioning school for all: the school environment as a protective factor for young people’s mental well-being]. Socialmedicinsk tidskrift [Soc Med]. 2020;97(5–6):804–16.

Google Scholar  

Bibou-Nakou I, Tsiantis J, Assimopoulos H, Chatzilambou P, Giannakopoulou D. School factors related to bullying: a qualitative study of early adolescent students. Soc Psychol Educ. 2012;15(2):125–45. https://doi.org/10.1007/s11218-012-9179-1 .

Vukojevic M, Zovko A, Talic I, Tanovic M, Resic B, Vrdoljak I, Splavski B. Parental socioeconomic status as a predictor of physical and mental health outcomes in children—literature review. Acta Clin Croat. 2017;56(4):742–8. https://doi.org/10.20471/acc.2017.56.04.23 .

Reiss F. Socioeconomic inequalities and mental health problems in children and adolescents: a systematic review. Soc Sci Med. 2013;90:24–31. https://doi.org/10.1016/j.socscimed.2013.04.026 .

Stockholm City. Stockholmsenkät (The Stockholm Student Survey). 2021. https://start.stockholm/aktuellt/nyheter/2020/09/presstraff-stockholmsenkaten-2020/ . Accessed 19 Nov 2021.

Zeebari Z, Lundin A, Dickman PW, Hallgren M. Are changes in alcohol consumption among swedish youth really occurring “in concert”? A new perspective using quantile regression. Alc Alcohol. 2017;52(4):487–95. https://doi.org/10.1093/alcalc/agx020 .

Hagquist C. Psychometric properties of the PsychoSomatic Problems Scale: a Rasch analysis on adolescent data. Social Indicat Res. 2008;86(3):511–23. https://doi.org/10.1007/s11205-007-9186-3 .

Hagquist C. Ungas psykiska hälsa i Sverige–komplexa trender och stora kunskapsluckor [Young people’s mental health in Sweden—complex trends and large knowledge gaps]. Socialmedicinsk tidskrift [Soc Med]. 2013;90(5):671–83.

Wu W, West SG. Detecting misspecification in mean structures for growth curve models: performance of pseudo R(2)s and concordance correlation coefficients. Struct Equ Model. 2013;20(3):455–78. https://doi.org/10.1080/10705511.2013.797829 .

Holt MK, Espelage DL. Perceived social support among bullies, victims, and bully-victims. J Youth Adolscence. 2007;36(8):984–94. https://doi.org/10.1007/s10964-006-9153-3 .

Mark L, Varnik A, Sisask M. Who suffers most from being involved in bullying-bully, victim, or bully-victim? J Sch Health. 2019;89(2):136–44. https://doi.org/10.1111/josh.12720 .

Tsaousis I. The relationship of self-esteem to bullying perpetration and peer victimization among schoolchildren and adolescents: a meta-analytic review. Aggress Violent Behav. 2016;31:186–99. https://doi.org/10.1016/j.avb.2016.09.005 .

Veldkamp SAM, Boomsma DI, de Zeeuw EL, van Beijsterveldt CEM, Bartels M, Dolan CV, van Bergen E. Genetic and environmental influences on different forms of bullying perpetration, bullying victimization, and their co-occurrence. Behav Genet. 2019;49(5):432–43. https://doi.org/10.1007/s10519-019-09968-5 .

Janssen I, Craig WM, Boyce WF, Pickett W. Associations between overweight and obesity with bullying behaviors in school-aged children. Pediatrics. 2004;113(5):1187–94. https://doi.org/10.1542/peds.113.5.1187 .

Kelly EV, Newton NC, Stapinski LA, Conrod PJ, Barrett EL, Champion KE, Teesson M. A novel approach to tackling bullying in schools: personality-targeted intervention for adolescent victims and bullies in Australia. J Am Acad Child Adolesc Psychiatry. 2020;59(4):508. https://doi.org/10.1016/j.jaac.2019.04.010 .

Gunnell D, Kidger J, Elvidge H. Adolescent mental health in crisis. BMJ. 2018. https://doi.org/10.1136/bmj.k2608 .

O’Reilly M, Dogra N, Whiteman N, Hughes J, Eruyar S, Reilly P. Is social media bad for mental health and wellbeing? Exploring the perspectives of adolescents. Clin Child Psychol Psychiatry. 2018;23:601–13.

Unnever JD, Cornell DG. Middle school victims of bullying: who reports being bullied? Aggr Behav. 2004;30(5):373–88. https://doi.org/10.1002/ab.20030 .

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HK conceived the study and analyzed the data (with input from MH). HK and MH interpreted the data and jointly wrote the manuscript. All authors read and approved the final manuscript.

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Källmén, H., Hallgren, M. Bullying at school and mental health problems among adolescents: a repeated cross-sectional study. Child Adolesc Psychiatry Ment Health 15 , 74 (2021). https://doi.org/10.1186/s13034-021-00425-y

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Consequences of Bullying

It is important for parents and people who work with children and adolescents to understand that bullying can have both short- and long-term effects on everyone involved. While most research on bullying has been about children and adolescents who have been bullied, those who bully others are also negatively impacted, as are those who are both bullied and bully others, and even those who are not directly involved but witness bullying.

Children Who Have Been Bullied

Research has found that children and adolescents who have been bullied can experience negative psychological, physical, and academic effects.

Psychological Effects

The psychological effects of bullying include depression, anxiety, low self-esteem, self-harming behavior (especially for girls), alcohol and drug use and dependence, aggression, and involvement in violence or crime (especially for boys). While bullying can lead to mental health problems for any child, those who already have mental health difficulties are even more likely to be bullied and to experience its negative effects.

Cyberbullying – bullying that happens with computers or mobile devices – has also been linked to mental health problems. Compared with peers who were not cyberbullied, children who were cyberbullied report higher levels of depression and thoughts of suicide, as well as greater emotional distress, hostility, and delinquency.

Physical Effects

Bullying and Suicide

Bullying is a risk factor for depression and thinking about suicide. Children who bully others, are bullied, or both bully and are bullied are more likely to think about or attempt suicide than those who are not involved in bullying at all.

The physical effects of bullying can be obvious and immediate, such as being injured from a physical attack. However, the ongoing stress and trauma of being bullied can also lead to physical problems over time. A child who is bullied could develop sleep disorders - such as difficulty falling asleep or staying asleep - stomachaches, headaches, heart palpitations, dizziness, bedwetting, and chronic pain and somatization (i.e., a syndrome of distressful, physical symptoms that cannot be explained by a medical cause).

Being bullied also increases cortisol levels – a stress hormone – in the body, which typically happens after a stressful event. Stress from bullying can impact the immune system and hormones. Imaging studies show that brain activity and functioning can be affected by bullying, which may help explain the behavior of children who have been bullied.

Academic Effects

Research has consistently shown that bullying can have a negative impact on how well children and adolescents do in school. It has a negative impact on both grades and standardized test scores starting as early as kindergarten and continuing through high school.

Children Who Bully and Those Who Witness Bullying

Very little research has been done to understand the effects of bullying on children who bully, and those who witness bullying (e.g., bystanders). More research is needed to understand the consequences of bullying on the individuals who bully others, particularly to understand the differences between those who are generally aggressive and those who bully others.

Studies of children who witness bullying usually focus on their role in the bullying situation (e.g., if they backed up the child who bullied, or defended the victim) and why they did or did not intervene. While studies rarely assess the effects of bullying exposure on the witness, some research has found that bullying witnesses experience anxiety and insecurity based on their own fears of retaliation.

Children Who Bully and Are Also Bullied

Children and adolescents who bully others and who are also bullied are at the greatest risk for negative mental and physical health consequences, compared to those who only bully or are only being bullied. These children and adolescents may experience a combination of psychological problems, a negative perception of themselves and others, poor social skills, conduct problems, and rejection by their peer group.

Compared with non-involved peers, those who have bullied others and have also been bullied have been found to be at increased risk for serious mental illness, be at high risk for thinking about and attempting suicide, and demonstrate heightened aggression.

Exposure to bullying in any manner – by being bullied, bullying others, or witnessing peers being bullied – has long-term, negative effects on children. The School Crime Supplement to the National Crime Victimization Survey found that in 2015, about 21 percent of students ages 12-18 reported being bullied at school during the school year. Given the prevalence of youth exposed to bullying across the nation, it is important to understand the consequences of bullying on children and adolescents, how it relates to other violent behaviors and mental health challenges, in order to effectively address them.

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Source and Research Limitations

The information discussed in this fact sheet is based on the comprehensive review of bullying research presented in the National Academies of Sciences, Engineering, and Medicine’s report entitled Preventing Bullying Through Science, Policy, and Practice .

This report includes the most up to date research on bullying, but it is important to note that this research has several important limitations. Most of the research is cross-sectional, which means it took place at one point in time. This type of research shows us what things are related to each other at that time, but cannot tell us which thing came first or if one of those things caused the other to occur.

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Committee on the Biological and Psychosocial Effects of Peer Victimization: Lessons for Bullying Prevention; Board on Children, Youth, and Families; Committee on Law and Justice; Division of Behavioral and Social Sciences and Education; Health and Medicine Division; National Academies of Sciences, Engineering, and Medicine; Rivara F, Le Menestrel S, editors. Preventing Bullying Through Science, Policy, and Practice. Washington (DC): National Academies Press (US); 2016 Sep 14.

Preventing Bullying Through Science, Policy, and Practice.

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4 Consequences of Bullying Behavior

Bullying behavior is a serious problem among school-age children and adolescents; it has short- and long-term effects on the individual who is bullied, the individual who bullies, the individual who is bullied and bullies others, and the bystander present during the bullying event. In this chapter, the committee presents the consequences of bullying behavior for children and youth. As referenced in Chapter 1 , bullying can be either direct or indirect, and children and youth may experience different types of bullying. Specifically the committee examines physical (including neurobiological), mental, and behavioral health consequences. The committee also examines consequences for academic performance and achievement and explores evidence for some of the mechanisms proposed for the psychological effects of bullying. When applicable, we note the limited, correlational nature of much of the available research on the consequences of bullying.

• CONSEQUENCES FOR INDIVIDUALS WHO ARE BULLIED

Mounting evidence on bullying has highlighted the detrimental effects of being bullied on children's health and behavior ( Gini and Pozzoli, 2009 ; Lereya et al., 2015 ; Reijntjes et al., 2010 ; Ttofi et al., 2011 ). In this section, the committee reviews the research on physical, psychosocial, and academic achievement consequences for those children and youth who are bullied.

Perspectives from the Field

Being bullied makes young people incredibly insecure: When you're being bullied, you can feel constantly insecure and on guard. Even if you're not actively being bullied, you're aware it could start anytime. It has a big mental and emotional impact—you feel unaccepted, isolated, angry, and withdrawn. You're always wondering how you can do better and how you can escape a bully's notice. You're also stunted because of the constant tension and because maybe you forego making certain friendships or miss out on taking certain chances that could actually help your development.

—Summary of themes from young adults focus group (See Appendix B for additional highlights from interviews.)

Physical Health Consequences

The physical health consequences of bullying can be immediate, such as physical injury, or they can involve long-term effects, such as headaches, sleep disturbances, or somatization. 1 However, the long-term physical consequences of bullying can be difficult to identify and link with past bullying behavior versus being the result of other causes such as anxiety or other adverse childhood events that can also have physical effects into adulthood ( Hager and Leadbeater, 2016 ). In one of the few longitudinal studies on the physical and mental effects of bullying, Bogart and colleagues (2014) studied 4,297 children and their parents from three urban locales: Birmingham, Alabama; 25 contiguous school districts in Los Angeles County, California; and one of the largest school districts in Houston, Texas. Bogart and her team were interested in the cumulative effects of bullying on an individual. They collected data when the cohort was in fifth grade (2004 to 2006), seventh grade (2006 to 2008), and tenth grade (2008 to 2010). Data consisted of responses to the Peer Experience Questionnaire, the Pediatric Quality of Life Inventory with its Psychosocial Subscale and Physical Health Subscale, and a Self-Perception Profile. The Physical Health Subscale measured perceptions of physical quality of life.

Bogart and colleagues (2014) found that children who were bullied experienced negative physical health compared to non-involved peers. Among seventh grade students with the worst-decile physical health, 6.4 percent were not bullied, 14.8 percent had been bullied in the past only, 23.9 percent had been bullied in the present only, and nearly a third (30.2%) had been bullied in both the past and present. These effects were not as strong when students were in tenth grade. Limitations to this study were that physical health was measured by participants' perceptions of their health-related quality of life, rather than by objectively defined physical symptoms. It is critical to understand that this study, or other studies assessing correlations between behavior and events, cannot state that the events caused the behavior. Future research might build on this large multisite longitudinal study and obtain more in-depth evidence on individuals' physical health as a consequence of bullying.

In their study of 2,232 twins reared together and separately as a part of the Environmental Risk (E-Risk) Longitudinal Twin Study, Baldwin and colleagues (2015) found that children who had experienced chronic bullying showed greater adiposity subsequently, but not at the time of victimization. The study revealed that at age 18, these children had a higher body mass index ( b = 1.11, CI [0.33, 1.88]), waist-hip ratio ( b = 0.017, CI [0.008, 0.026]), and were at a higher risk of being overweight ( OR = 1.80, CI [1.28, 2.53]) than their nonbullied counterparts ( Baldwin et al., 2015 ).

An important future direction for research is to gather more information on physical consequences such as elevated blood pressure, inflammatory markers, and obesity in light of work showing effects on these outcome of harsh language by parents and other types of early life adversity ( Danese and Tan, 2014 ; Danese et al., 2007 ; Evans et al., 2007 ; Miller and Chen, 2010 ).

Somatic Symptoms

Most of the extant evidence on the physical consequences—somatic symptoms in particular—of bullying pertains to the individual who is bullied. The emotional effects of being bullied can be expressed through somatic disturbances, which, similar to somatization, are physical symptoms that originate from stress or an emotional condition. Common stress or anxiety-related symptoms include sleep disorders, gastrointestinal concerns, headaches, palpitations, and chronic pain. The relationship between peer victimization and sleep disturbances has been well documented ( Hunter et al., 2014 ; van Geel et al., 2014 ).

For instance, Hunter and colleagues (2014) examined sleep difficulties (feeling too tired to do things, had trouble getting to sleep, and had trouble staying asleep) among a sample of 5,420 Scottish adolescents. The researchers found that youth who were bullied ( OR = 1.72, 95% CI [1.07, 2.75]) and youth who bully ( OR = 1.80, CI [1.16, 2.81]) were nearly twice as likely as youth who were not involved in bullying to experience sleep difficulties. One limitation of this study is that it was based on self-reports, which have sometimes been criticized as being subject to specific biases. Patients with insomnia may overestimate how long it takes them to fall asleep ( Harvey and Tang, 2012 ). Another limitation is that the study included young people at different stages of adolescence. Sleep patterns and sleep requirements vary across the different stages of adolescence.

A recent meta-analysis based on 21 studies involving an international sample of 363,539 children and adolescents examined the association between peer victimization and sleeping problems. A broader focus on peer victimization was used because of the definitional issues related to bullying. The authors defined peer victimization as “being the victim of relational, verbal or physical aggression by peers” ( van Geel et al., 2015 , p. 89). Children and youth who were victimized reported more sleeping problems than children who did not report victimization ( OR = 2.21, 95% CI [2.01, 2.44]). Moreover, the relationship between peer victimization and sleeping problems was stronger for younger children than it was for older children ( van Geel et al., 2015 ). This study was based on cross-sectional studies that varied widely in how peer victimization and sleeping problems were operationalized and thus cannot make any claims about causal relations between peer victimization and sleeping problems.

Knack and colleagues (2011a) posited that bullying results in meaningful biological alterations that may result in changes in one's sensitivity to pain responses. A recent meta-analysis by Gini and Pozzoli (2013) concluded that children and adolescents who are bullied were at least twice as likely to have psychosomatic disturbances (headache, stomachache, dizziness, bedwetting, etc.) than nonbullied children and adolescents ( OR = 2.39, 95% CI [1.76, 3.24] for longitudinal studies; OR = 2.17, 95% CI [1.91, 2.46] for cross-sectional studies). Although the use of self-report measures are very common in bullying research and are usually considered to be valid and reliable (Ladd and Kochenderfer- Ladd, 2002 ), their use requires adequate self-awareness on the part of the respondent, and some children who are bullied may be in denial about their experience of having been bullied.

There is also evidence of gender differences in the physical effects of being bullied. For example, Kowalski and Limber (2013) examined the relation between experiences with cyberbullying or traditional bullying (i.e., bullying that does not involve digital electronic means of communication) and psychological and physical health, as well as academic performance, of 931 students in grades 6 through 12 living in rural Pennsylvania. Students were asked how often in the past 4 weeks they experienced 10 physical health symptoms, with scores across these 10 symptoms averaged to provide an overall health index (higher scores equal more health problems). Traditional bullying was defined as “aggressive acts that are meant to hurt another person, that happen repeatedly, and that involve an imbalance of power” ( Kowalski and Limber, 2013 , p. S15). The authors found that girls who were traditionally bullied reported more anxiety and overall health problems than boys who were bullied (females: M = 1.65, SD = 0.41; males: M = 1.42, SD = 0.38). A limitation of this study is that it is correlational in nature and the authors cannot conclude that being a victim of traditional bullying caused the psychological or physical problems.

In summary, it is clear that children and youth who have been bullied also experience a range of somatic disturbances. There are also gender differences in the physical health consequences of being bullied.

Neuroendocrinology of Stress

Psychological and physical stressors, such as being the target of bullying, activate the stress system centered on the hypothalamic-pituitary-adrenal (HPA) axis ( Dallman et al., 2003 ; McEwen and McEwen, 2015 ). The role of HPA and other hormones is to promote adaptation and survival, but chronically elevated hormones can also cause problems. Stress has ubiquitous effects on physiology and the brain, alters levels of many hormones and other biomarkers, and ultimately affects behavior. Therefore, both a general understanding of stress during early adolescence and, where known, specific links between stress and bullying can provide insight into the enduring effects of bullying.

The levels of the stress hormone cortisol have been shown to change in targets of repeated bullying, with being bullied associated with a blunted cortisol response ( Booth et al., 2008 ; Kliewer, 2006 ; Knack et al., 2011b ; Ouellet-Morin et al., 2011 ; Vaillancourt et al., 2008 ). To the committee's knowledge, no study has examined bidirectional changes in cortisol, although there is evidence to suggest that cortisol is typically elevated immediately following many types of stress and trauma but blunted after prolonged stress ( Judd et al., 2014 ; Miller et al., 2007 ). Kliewer (2006) did find that cortisol increased from pre-task to post-task (i.e., watching a video clip from the film Boyz 'n the Hood followed by a discussion) among youth who had been bullied, and in a more recent study, Kliewer and colleagues (2012) reported, among African American urban adolescents, that peer victimization was associated with greater sympathetic nervous system (fight or flight reaction) reactivity to a stress task (measured using salivary a-amylase, an enzyme that increases in saliva when the sympathetic nervous system is activated). However, in these studies, the immediate effect of being bullied on stress reactivity was not examined. In contrast, Ouellet-Morin and colleagues (2011) and Knack and colleagues (2011b) did not find an increase in cortisol in bullied youth following a psychosocial stress test but rather found a blunted pattern of response after the test had concluded (see Figures 4-1 and 4-2 ). In order to test whether, in the short-term, bullying produces an increase in cortisol, whereas in the long-term it is associated with a blunted cortisol response (as seen with other types of psychosocial stressors; Judd et al., 2014 ; Miller et al., 2007 ), a longitudinal study is needed to examine bullying chronicity and regulation of the HPA axis. The importance of this future work notwithstanding, there is evidence to support a finding that when stress becomes prolonged, the stress hormone system becomes hypofunctional and a blunted stress response results ( McEwen, 2014 ).

Cortisol reactivity for victimized and nonvictimized adolescents during the Trier Social Stress Test. SOURCE: Adapted from Knack et al. (2011b, Fig. 3, p. 5).

Cortisol responses to a psychosocial stress test (PST) in the total sample and according to maltreatment/bullying victimization. SOURCE: Adapted from Ovellet-Morin et al. (2011, Fig. 1, p. 14).

When stress becomes prolonged, the stress hormone system becomes hypofunctional and a blunted stress response results ( Knack et al., 2012a ; McEwen, 2014 ; Vaillancourt et al., 2013a ). That is, the elevation in cortisol in response to stress fails to occur. Scientists are not exactly sure how this happens, but evidence suggests that the stress system has shut itself down through “negative feedback.” Although on the surface this may seem to be beneficial, it is not. Cortisol has many functions and serves to regulate myriad biological systems; a blunted stress response compromises the orchestration of cortisol's biological functions. The critical importance of the massive over-activation of the stress system producing a blunted stress response is clinically relevant since it is associated with posttraumatic stress disorder and other psychiatric disorders ( Heim et al., 1997 ). It is also relevant for understanding an individual's inability to self-regulate and cope with stress.

Prolonged stress also disrupts the circadian or daily rhythm of cortisol, which is normally elevated in the morning and slowly decreases over the day to result in low levels at bedtime ( Barra et al., 2015 ). An altered circadian rhythm results not only in difficulty awaking in the morning but also in difficulty falling asleep at night. It can cause profound disruption in sleep patterns that can initiate myriad additional problems; sleep deficits are associated with problems with emotional regulation, learning, mood disorders, and a heightened social threat detection and response system ( McEwen and Karatsoreos, 2015 ). Recent research suggests that the consolidation of memories 2 one learns each day continues during sleep ( Barnes and Wilson, 2014 ; Shen et al., 1998 ). Sleep disturbances disrupt memory consolidation, and studies in animals suggest stress during learning engages unique neurochemical and molecular events that cause memory to be encoded by some unique mechanism ( Baratta et al., 2015 ; Belujon and Grace, 2015 ; McGaugh, 2015 ; Rau and Fanselow, 2009 ). Although victims of bullying have sleep problems ( Miller-Graff et al., 2015 ), causal relations between bullying, sleep disorders, learning/memory consolidation, and cortisol dysregulation have not been established. Indeed, these correlations between being a target of bullying and physiological problems may highlight important interactions between events and outcome, but it is also likely that unidentified variables might be the critical causal factors.

It is also noteworthy that the HPA axis showed heightened responsiveness during the peak ages of bullying ( Blakemore, 2012 ; Dahl and Gunnar, 2009 ; Romeo, 2010 ; Spear, 2010 ). For example, cortisol response characteristics in children are such that, when cortisol is activated, the hormonal response is protracted and takes almost twice as much time to leave the blood and brain compared to adults ( Romeo, 2010 , 2015 ). The circadian rhythm of cortisol also seems altered during early adolescence, most notably associated with morning cortisol levels, with levels increasing with age and pubertal development ( Barra et al., 2015 ). Animal models suggest that the extended cortisol response begins in pre-puberty and indicate that recovery from stressful events is more challenging during this age range ( Romeo, 2015 ).

Emotional regulation, including a person's ability to recover from a traumatic or stressful event, involves being able to regulate or normalize stress hormone levels. Before adolescence, children's ability to regulate their stress response can be greatly assisted by parents or other significant caregivers—a process referred to as “social buffering” ( Hostinar et al., 2014 ; Ouellet-Morin et al., 2011 , 2013 ). Specifically, it is well documented in the human and animal research literature that a sensitive caregiver or a strong support system can greatly dampen the stress system's response and actually reduce the amount of stress hormone released, as well as shorten the amount of time the stress hormones circulate within the body and brain. This results in dramatic decreases in stress-related behavior ( Gee et al., 2014 ; Hostinar et al., 2014 ). The social cues actually reduce stress by reducing the activation of the stress system, or HPA axis, at the level of the hypothalamus ( Hennessy et al., 2009 , 2015 ; Moriceau and Sullivan, 2006 ). The social stimuli that buffer children as they transition into adolescence appear to begin to have greater reliance on peers rather than on the caregiver ( Hostinar et al., 2015 ).

Other physiological effects of stress include the activation of the immune system by bullying-induced stress ( Copeland et al., 2014 ; McCormick and Mathews, 2007 ), and a cardiovascular blunting among individuals with a history of being bullied ( Newman, 2014 ). Other hormones and physiological mechanisms are also involved in the stress activation response. For example, cortisol is associated with an increase in testosterone, the male sex hormone associated with aggression in nonhuman animals and with dominance and social challenge in humans, particularly among boys and men ( Archer, 2004 ). In fact, in rodents the combined assessment of testosterone and cortisol provides more predictive value of behavioral variability ( McCormick and Mathews, 2007 ) compared to controls ( Márquez et al., 2013 ). In humans, there is increasing evidence supporting an interaction between testosterone and cortisol in the prediction of social aggression (see Montoya et al., 2012 ). In a study of 12-year-olds, Vaillancourt and colleagues (2009) found that testosterone levels were higher among bullied boys than nonbullied boys, but lower among bullied girls than nonbullied girls. The authors speculated that the androgen dynamics were possibly adrenocortical in origin, highlighting the need to examine testosterone and cortisol in consort. To date, researchers have only investigated cortisol response to being bullied ( Kliewer, 2006 ; Knack et al., 2011b ; Ouellet-Morin et al., 2011 ; Vaillancourt et al., 2008 ), and only one study has examined testosterone and peer victimization ( Vaillancourt et al., 2009 ). There are no studies examining these two important hormones together in relation to bullying perpetration or to being bullied.

Together, the research on both humans and animals suggests that stress is beneficial when it is experienced at low-to-moderate levels, whereas prolonged or repeated stress becomes toxic by engaging a unique neural and molecular cascade within the brain that is thought to initiate a different developmental pathway. Indeed, from animal models, brain architecture is altered by chronic stress, with amygdala activity being enhanced, hippocampal function impaired, and medial prefrontal cortex function being reduced, leading to increased anxiety and aggression and decreased capacity for self-regulation, as well as a more labile mood ( Chattarji et al., 2015 ; McEwen and Morrison, 2013 ; McEwen et al., 2015 ). This stress effect on the brain is particularly strong when experienced during adolescence, but it is even more pronounced if combined with early life adversity ( Gee et al., 2014 ; Hanson et al., 2015 ; Richter-Levin et al., 2015 ; Romeo, 2015 ; Sandi and Haller 2015 ). This could produce behavioral responses that become maladaptive by compromising emotional and cognitive functioning or perhaps it could produce adaptive behavior for a dangerous environment that results in socially inappropriate behavior.

Consequences of Bullying on Brain Function

Being a child or youth who is bullied changes behavior, and neuroscience research suggests this experience may also change the brain ( Bradshaw et al., 2012 ; Vaillancourt et al., 2013a ). The major technique used to monitor brain function in humans is functional magnetic resonance imaging (fMRI), which works by monitoring blood flow to indirectly assess the functioning of thousands of brain cells over an area of the brain. This technique has rarely been used on either the perpetrator or target of a bullying incident during this very particular social interaction, and for that reason little is known about whether or not the brain of a child who bullies or of a child who has been bullied is different before these experiences or is changed by them. These very specific studies are required before one can make definitive statements about the brain for this topic or for how this information might help develop novel interventions or prevention.

Additionally, it is important to consider two limitations for understanding fMRI. First, one cannot scan the brain of a child during the action of bullying or being a target of bullying. Instead, one must rely on the child staying perfectly still as the investigator tries to approximate one or two aspects of the complex experience that occur in this complicated behavioral interaction. For example, the fMRI task used during a brain imaging session might mimic social exclusion as one facet of bullying, without the full social and emotional context of the real bullying process. Although this is an important methodology, these results need to be assessed with caution at this time and not directly applied as an accepted scientific interpretation of bullying. Therefore, the examples used below to assess brain function rely not on monitoring actual instances of bullying behavior but on monitoring components of behaviors that are thought to occur during a bullying incident.

Second, fMRI monitors a large brain area, which is composed of many smaller brain areas, each of which is involved in many, many behaviors, many of which are not yet fully understood. Thus, it is difficult to determine why the brain area one is examining changed, since that brain area is involved in hundreds of diverse behaviors. For this reason, the results reviewed below need to be viewed as preliminary and should not be misinterpreted as explaining any aspect of the experience of bullying. Rather, these preliminary results highlight the importance of brain assessment before and after bullying experiences, including developing monitorable tasks that more closely approximate the bullying experience within the physical constraints of an immobile subject during an fMRI brain scan. The value of neuroscience is that it enables exploration of brain mechanisms controlling behavior that are not obvious from behavioral assessment.

Social Pain

Whereas there are no studies directly examining bullying using neural imaging techniques, there are several studies examining how the brain processes social pain. Social pain describes the “feelings of pain that follow the experiences of peer rejection, ostracism, or loss” ( Vaillancourt et al., 2013a , p. 242). Social pain is consistent with how people describe their feeling about being bullied. For example, one victim of bullying described the emotional toll of his experience by saying, “I feel like, emotionally, they [his bullies] have been beating me with a stick for 42 years” ( Vaillancourt et al., 2013a , p. 242).

Researchers have demonstrated that when people experience social pain, they activate regions in their brain similar to those activated when they experience physical pain ( Eisenberger, 2012 ; Eisenberger and Lieberman, 2004 ; Eisenberger et al., 2003 ; Kross et al., 2011 ; Vaillancourt et al., 2010a ). Specifically, the dorsal anterior cingulate cortex, which is part of the prefrontal cortex, seems to be implicated in the processing of both physical and social pain. The fact that physical and social pain have overlapping neural systems might explain why people tend to use physical pain metaphors (e.g., “It broke my heart when she called me ugly.”) when describing their experiences with being humiliated, oppressed, or rejected ( Eisenberger, 2012 ). Eisenberger and Leiberman (2004) noted that these fMRI results are correlations between pain and the anterior cingulate cortex and could reflect other functions of that brain region, such as detecting conflict or errors, different ideas or goals about the task, or individual differences in the task difficulty. In a recent fMRI study by Rudolph and colleagues (2016) , adolescent girls were socially excluded during a laboratory task (i.e., cyberball; Williams et al., 2000 ). Results indicated that activation of the social pain network—the dorsal anterior cingulate cortex, subgenual anterior cingulate cortex, and anterior insula—was associated with internalizing symptoms. Of note, this effect was particularly pronounced among adolescent girls with a history of peer victimization. 3

In addition to studies on social pain, there are some studies examining how the brains of children who had been bullied reacted subsequently to different stimuli. Experiences of being bullied can alter an individual's view of the world. While no brain imaging study has directly addressed this issue, a longitudinal study investigating the risk factors of depression found that being a child who was bullied at ages 11 and 12 was associated with a decreased response to reward in the medial prefrontal cortex at age 16, although it was unclear if these brain differences were present before the bullying experiences or developed after them ( Casement et al., 2014 ). The medial prefrontal cortex, which is a brain area involved in memory and learning, was found to be disrupted in children who have been bullied ( Vaillancourt et al., 2011 ). Because it also has countless other functions including decision making, risk taking, and conflict monitoring, disruption of this region compromises one's ability to interpret results with respect to bullying ( Euston et al., 2012 ; Vaillancourt et al., 2011 ).

In another fMRI study involving children, 10-12 years old, who were presented with a task that examined their response to negative feedback stimuli of emotional faces, greater and more extensive brain activation was found in the amygdala, orbitofrontal cortex, and ventrolateral prefrontal cortex of children who had been rejected by their peers, compared with children in a control group who had not been rejected by peers ( Lee et al., 2014 ), a condition that is highly correlated with being bullied by peers ( r = .57; Knack et al., 2012a ). The prefrontal cortex is a very large brain area with many subareas, all of which serve diverse functions in many different behaviors, not just executive function. Indeed, the prefrontal cortex processes pain, self-regulation, stress integration, and safety signals and has been implicated in psychiatric disorders, higher order learning, extinction (active process to suppress a memory), personality, social behavior, planning, decision making, and many other behaviors and percepts including social exclusion, social/physical pain, and empathy ( Casey and Jones, 2010 ; Spear, 2013 ). These few studies are consistent with other imaging studies demonstrating functional brain differences among individuals who were maltreated in childhood ( Lim et al., 2014 , 2015 ). Taken together, this work supports a finding that being exposed to such adversity during maturation has enduring effects on brain function, although additional research is needed to establish the parameters controlling these effects (and qualifying the generalization).

There is also evidence that stressful events, such as might occur with bullying experiences, impact emotional brain circuits, an inference that is supported by changes in amygdala architecture and function described earlier in animal models in adulthood but more robust changes in brain structure are produced by stress during early life and around adolescence ( Chattarji et al., 2015 ; McEwen and Morrison, 2013 ; McEwen et al., 2015 ). This point is critical because the stress system of adolescents seems to have a heightened sensitivity, and experiencing bullying can increase stress hormones ( Romeo, 2010 , 2015 ; Spear, 2013 ; Vaillancourt et al., 2011 ). Human brain scanning experiments suggest the prefrontal cortex is affected by stress through attenuating the connectivity to the hippocampus and amygdala, which are brain areas critical for emotional regulation and emotional memories ( Ganzel et al., 2008 ; Liston et al., 2009 ). Animal research shows that this connectivity loss is caused by stress-induced atrophy of the prefrontal cortex ( Radley et al., 2006 ), although this brain region does show the ability to recover once the stress has terminated ( Liston et al., 2009 ). One aspect of being a target of bullying is that the memory of the experience seems to be enduring; the unique function of the prefrontal cortex and emotional circuits during preadolescence and adolescence may provide insight into the enduring memories of being bullied. Specifically, one function of the prefrontal cortex is to help suppress memories that are no longer important or true. Typically, memories are not simply forgotten or unlearned. Rather, as we update information in our brain, the old memory is suppressed by overlaying a new memory to attenuate the old memory, an active brain process called extinction ( Milaid and Quirk, 2012 ). With respect to memories of trauma, of being bullied, or of experiencing a threat, the prefrontal cortex is important for attenuating (extinguishing) memories in emotional brain areas, such as the amygdala. Importantly, dramatic changes occur in the extinction system during adolescence, where fear extinction learning is attenuated relative to children and adults ( Pattwell et al., 2012 , 2013 ). This learning mode has been modeled in animals to understand how the process occurs in the adolescent brain ( Kim and Richardson, 2010 ; Nair and Gonzalez-Lima, 1999 ; Pattwell et al., 2012 ). The research suggests that around the time of adolescence, it is more difficult to decrease emotionally aversive memories, such as experiences of being bullied, than at other times in the life cycle. Furthermore, anxious teens (anxiety is sometimes comorbid with experience of being bullied) show even greater difficulties with processing extinction of fear memory ( Jovanovic et al., 2013 ).

In conclusion, the available evidence indicates that the brain functioning of individuals who are bullied is altered (see reviews by Bradshaw et al., 2012 ; Vaillancourt et al., 2013a ). However, it is difficult to ascertain fully what it means when fMRI scans detect an alteration in brain activity. In terms of understanding the prolonged and repeated stress associated with bullying, this research suggests that greater experience with being bullied and repeated exposure as a target of bullying produces a neural signature in the brain that could underlie some of the behavioral outcomes associated with being bullied.

Psychosocial Consequences

In this section, the committee examines what is known about the psychosocial consequences of being bullied. A common method of examining mental health issues separates internalizing and externalizing problems ( Sigurdson et al., 2015 ). Internalizing symptoms include problems directed within the individual, such as depression, anxiety, fear, and withdrawal from social contacts. Externalizing symptoms reflect behavior that is typically directed outwards toward others, such as anger, aggression, and conduct problems, including a tendency to engage in risky and impulsive behavior, as well as criminal behavior. Externalizing problems also include the use and abuse of substances.

Psychological problems are common after being bullied (see review by Hawker and Boulton, 2000 ) and include internalizing problems, such as depression, anxiety, and, especially for girls, self-harming behavior ( Kidger et al., 2015 ; Klomek et al., 2009 , 2015 ). There can also be subsequent externalizing problems, especially for boys (see review by McDougall and Vaillancourt, 2015 ). Rueger and colleagues (2011) found consistent concurrent association with timing of peer victimization and maladjustment. Both psychological and academic outcomes were particularly strong for students who experienced sustained victimization over the school year.

“And these are the kids that are at risk for anxiety and depression and bipolar disorder to begin with, and it almost seems like it's a cycle that makes it worse. So they are isolated and they are angry, they are fearful. Many of them end up severely depressed, attempting suicide, utilizing NSSIs [nonsuicidal self-injuries] for comfort. Some turn to gangs because that is the group that would accept them. So that's when we get involved and we have to start working backwards.”

—Quote from community-based provider discussing bullying during focus group (See Appendix B for additional highlights from interviews.)

Internalizing Problems

A robust literature documents that youth who are bullied often have low self-esteem and feel depressed, anxious, and lonely ( Juvonen and Graham, 2014 ). Data from developmental psychopathology research indicate that stressful life events can lead to the onset and maintenance of depression, anxiety, and other psychiatric symptoms and that for many youth, being bullied is a major life stressor ( Swearer and Hymel, 2015 ). Based on sociometric nominations, targets of bullying also are disliked by the general peer group ( Knack et al., 2012b ).

Several meta-analyses have specifically explored the relation between depression and being bullied at school ( Ttofi et al., 2011 ) and victimized by peers 4 ( Hawker and Boulton, 2000 ; Reijntjes et al., 2010 ). Individuals who had been cyberbullied reported higher levels of depression and suicidal ideation, as well as increased emotional distress, externalized hostility, and delinquency, compared with peers who were not bullied ( Patchin, 2006 ; Ybarra et al., 2006 ). Furthermore, severity of depression in youth who have been cyberbullied has been shown to correlate with the degree and severity of cyberbullying ( Didden et al., 2009 ).

Two meta-analyses found that across several different longitudinal studies using different study populations, internalizing emotional problems increases both the risk and the harmful consequences of being bullied ( Cook et al., 2010 ; Reijntjes et al., 2010 ). Internalizing problems can thus function as both antecedents and consequences of bullying ( Reijntjes et al., 2010 ; Vaillancourt et al., 2013b ). Although most longitudinal studies suggest that psychological problems result from being bullied (see review by McDougall and Vaillancourt, 2015 ) and meta-analyses ( Reijntjes et al., 2010 ; Ttofi et al., 2011 ) support this directionality, there is some evidence that for some youth, the temporal pattern begins with mental health problems ( Kochel et al., 2012 ; Vaillancourt et al., 2013b ).

In a large cohort of Canadian children followed every year from grade 5 to grade 8, Vaillancourt and colleagues (2013b) found that internalizing problems in grades 5 and 7 predicted increased self-reported bullying behavior the following year. They noted that these findings provide evidence for the “symptom-driven pathway” across time with increased internalizing problems predicting greater self-reported peer victimization. This “symptom-drive pathway” was noted from grade 5 to grade 6 and again from grade 7 to grade 8 and was consistent with other published work. For instance, Kochel et al. (2012) reported a symptom-driven pathway in which depressive symptoms predicted peer victimization 5 1 year later (grade 4 to grade 5 and grade 5 to grade 6) and argued that this pathway may result from depressed youth displaying “social deficits,” selecting “maladaptive relationships,” and/or displaying a behavioral style that is perceived poorly by the peer group ( Kochel et al., 2012 , p. 638). Vaillancourt and colleagues (2013b) have also argued that depressed youth could be more “treat sensitive.” That is, these youth may select information from their environment that is consistent with their negative self-opinion. The idea that certain individuals may be more sensitive to environmental cues or make more hostile interpretation of ambiguous social data has been well documented in the literature ( Crick and Dodge, 1994 ; Dodge, 1986 ). This work is consistent with studies showing that social information processing differs in children based on their experience with being bullied and that hypersensitivity can impact their interpretation of social behavior and their self-reports of subsequent incidents of being bullied ( Camodeca et al., 2003 ; Smalley and Banerjee, 2013 ).

Most longitudinal studies to date are of relatively short duration (i.e., less than 2 years) and focus on a narrow developmental period such as childhood or adolescence ( McDougall and Vaillancourt, 2015 ). Nevertheless, there are several recently published studies examining the long-term adult outcomes of childhood bullying. These studies indicate that being bullied does affect future mental health functioning, as reviewed in the following paragraphs.

Most long-term studies of childhood bullying have focused on links to internalizing problems in adulthood, demonstrating robust long-standing effects ( Gibb et al., 2011 ; Olweus, 1993b ; Sourander et al., 2007 ; Stapinski et al., 2014 ). For example, Bowes and colleagues (2015) examined depression in a large sample of participants who reported being the target of bullying at age 13 and found higher rates of depression at age 18 compared to peers who had not been bullied. Specifically, they reported that 14.8 percent of participants who reported being frequently bullied in childhood at age 13 were clinically depressed at age 18 ( OR = 2.96, 95% CI [2.21, 3.97]) and that the population attributable fraction was 29.2 percent, suggesting that close to a third of the variance in depression could be explained by being bullied in childhood ( Bowes et al., 2015 ).

In another longitudinal study using two large population-based cohorts from the United Kingdom (the ALSPAC Cohort) and the United States (the GSMS Cohort), Lereya and colleagues (2015) reported that the effects of childhood bullying on adult mental health were stronger in magnitude than the effects of being maltreated by a caregiver in childhood. Being bullied only (and not maltreated) placed individuals at higher risk for mental health difficulties than being maltreated only (and not bullied) ( OR = 1.6, 95% CI [1.1, 2.2] for ALSPAC cohort; OR = 3.8, 95% CI [1.8, 7.9] for GSMS cohort). Children who were bullied were more likely than maltreated children to be anxious ( OR = 4.9, 95% CI [2.0, 12.0] for GSMS cohort), depressed ( OR = 1.7, 95% CI [1.1, 2.7] for ALSPAC cohort), and to engage in self-harming behavior ( OR = 1.7, 95% CI [1.1-2.6] for ALSPAC cohort) in adulthood ( Lereya et al., 2015 ).

Similarly, Stapinski and colleagues (2014) found that adolescents who experienced frequent peer victimization 6 were two to three times more likely to develop an anxiety disorder 5 years later at age 18 than nonvictimized adolescents ( OR = 2.49, 95% CI [1.62, 3.85]). The association remained after adjusting for potentially confounding individual and family factors and was not attributable to diagnostic overlap with depression. Frequently victimized adolescents were also more likely to develop multiple internalizing problems in adulthood ( Stapinski et al., 2014 ). After controlling for childhood psychiatric problems or family hardship, Copeland and colleagues (2013) found that individuals who were bullied continued to have higher prevalence of generalized anxiety ( OR = 2.7, 95% CI [1.1, 6.3]).

These findings suggest that being bullied and internalizing problems such as depression are mutually reinforcing, with the experience of one increasing the risk of the other in a harmful cycle that contributes to the high stability of being both bullied and experiencing other internalizing problems. These studies also suggest that the long-term consequences of being bullied, which extend into adulthood, can be more severe than being maltreated as a child by a caregiver.

Externalizing Problems

Alcohol and drug abuse and dependence have been associated with being bullied as a child ( Radliff et al., 2012 ). A longitudinal study of adolescents found that those who reported being bullied were more likely to report use of alcohol, cigarettes, and inhalants 12 months later ( Tharp-Taylor et al., 2009 ), compared to those who did not report being bullied. More longitudinal research that tracks children through adulthood is needed to fully understand the link between being bullied and substance abuse (see review by McDougall and Vaillancourt, 2015 ).

Several studies show links between being bullied and violence or crime, especially for men ( Gibb et al., 2011 ; McGee et al., 2011 ; Sourander et al., 2007 , 2011 ). A meta-analysis by Reijntjes and colleagues (2011) that included studies with data on 5,825 participants showed that after controlling for externalizing symptoms at baseline, peer victimization—under which they included being the target of teasing, deliberate exclusion, and being the target of physical threats and malicious gossip—was associated over time with exhibiting externalizing problems such as aggression, truancy, and delinquency ( r = .14, 95% CI [.09, .19]). This research team also found that externalizing problems predicted changes in peer victimization over time ( r = .13, 95% CI [.04, .21]) and concluded that there is a bidirectional relationship between peer victimization and externalizing problems.

Psychotic Symptoms

Evidence from the broader research on childhood trauma and stress indicates that earlier adverse life experiences, such as child abuse, are associated with the development of psychotic symptoms later in life ( Institute of Medicine and National Research Council, 2014b ). Until recently, the association between bullying and psychotic symptoms has been understudied ( van Dam et al., 2012 ). Two recent meta-analyses support the association between bullying and the development of psychotic symptoms later in life ( Cunningham et al., 2015 ; van Dam et al., 2012 ). van Dam and colleagues (2012) conducted a meta-analysis of 14 studies to assess whether being bullied in childhood is related to the development of psychotic (either clinical or nonclinical) symptoms. (Nonclinical psychotic symptoms 7 place individuals at risk for the development of psychotic disorders ( Cougnard et al., 2007 ).) Results from the analyses of studies that examined the association between bullying and nonclinical symptoms (six studies) were more definitive (adjusted OR = 2.3; 95% CI [1.5, 3.4]), with stronger associations when there was an increased frequency, severity, and persistence of bullying ( Cougnard et al., 2007 ). Although some research has found this association, a recent longitudinal study from New Zealand found that the link between bullying and the development of psychosis later in life is likely not causal but instead reflects the fact that individuals who display disordered behaviors across childhood and adolescences are more likely to become bullying targets ( Boden et al., 2016 ) An analysis of studies that examined the association between bullying and psychosis in clinical samples was inconclusive ( van Dam et al., 2012 ).

A recent meta-analysis conducted by Cunningham and colleagues (2015) examined ten European prospective studies, four from the Avon Longitudinal Study of Parents and Children. This analysis found that individuals who were bullied were more than twice as likely to develop later psychotic symptoms, compared to those who were not bullied ( OR = 2.1, 95% CI [1.1, 4.0]). These results were consistent in all but one of the studies included in the meta-analysis. More longitudinal research is needed to more fully understand the mechanisms through which trauma such as bullying may lead to the development of psychotic symptoms ( Cunningham et al., 2015 ; van Dam et al., 2012 ). Importantly, this research will need to be prospective and examine the development of bullying and psychotic symptoms in order to truly identify the temporal priority. The inclusion criteria for the Cunningham and colleagues (2015) meta-analysis included that the study had to be prospective and had to include a measure of psychosis and that bullying needed to be reported before the age of 18. Although the authors stated that “bullying appears to cause later development of psychosis,” such a conclusion requires that mental health functioning be assessed early and over time, as it is possible that premorbid characteristics may make individuals targets for poor peer treatment (see Kochel et al., 2012 ; Vaillancourt et al., 2013b , regarding depression leading to peer victimization).

Academic Performance Consequences

A growing literature has documented that targets of bullying suffer diminished academic achievement whether measured by grades or standardized test scores ( Espelage et al., 2013 ; Nakamoto and Schwartz, 2010 ). Cross-sectional research indicates that children who are bullied are at increased risk for poor academic achievement ( Beran, 2009 ; Beran and Lupart, 2009 ; Beran et al., 2008 ; Glew et al., 2005 ; Neary and Joseph, 1994 ; see also meta-analysis by Nakamoto and Schwartz, 2010 ) and increased absenteeism ( Juvonen et al., 2000 ; Kochenderfer and Ladd, 1996 ; Vaillancourt et al., 2013b ).

The negative relation between being bullied and academic achievement is evident as early as kindergarten ( Kochenderfer and Ladd, 1996 ) and continues into high school ( Espinoza et al., 2013 ; Glew et al., 2008 ). In a 2-week daily diary study with ninth and tenth grade Latino students, Espinoza and colleagues (2013) reported that on days when adolescents' reports of being bullied were greater than what was typical for them, they also reported more academic challenges such as doing poorly on a quiz, test, or homework and felt like less of a good student. Thus, even episodic encounters of being bullied can interfere with a student's ability to concentrate on any given day. In a cross-sectional study of more than 5,000 students in grades 7, 9, and 11, Glew and colleagues (2008) found that for every 1-point increase in grade point average (GPA), the odds of being a child who was bullied (versus a bystander) decreased by 10 percent. However, due to the cross-sectional nature of this study, this association does not establish whether lower academic achievement among children who were bullied was a consequence of having been bullied.

Several short-term (one academic year) longitudinal studies indicate that being bullied predicts academic problems rather than academic problems predicting being a target of bullying ( Kochenderfer and Ladd, 1996 ; Schwartz et al., 2005 ). Given the impairments in brain architecture associated with self-regulation and memory in animal models and the currently limited imaging data in human subjects, this is a reasonable inference, although reverse causation is possible. For instance, early life abuse and neglect impair these same abilities, lower self-esteem, and may make an individual more likely to be a target of bullying. In one of the few longitudinal studies to extend beyond one year, Juvonen and colleagues (2011) examined the relation between victimization 8 and academic achievement across the three years of middle school. Academic adjustment was measured by both year-end grades and teacher reports of engagement. These authors found that more self-reported victimization was related to lower school achievement from sixth to eighth grade. For every 1-unit increase in victimization (on a 1-4 scale), GPA declined by 0.3 points.

Other short-term longitudinal studies found similar results. For example, Nansel and colleagues (2003) found that being bullied in a given year (grade 6 or 7) predicted poor academic outcomes the following year, after controlling for prior school adjustment and if they were previously targets of bullying or not. Similarly, Schwartz and colleagues (2005) reported a negative association for third and fourth grade children between victimization 9 and achievement 1 year later. In addition, Baly and colleagues (2014) found that the cumulative impact of being bullied over 3 years from sixth grade to eighth grade had a negative impact on GPA and standardized test scores.

However, other studies have not found such associations. For instance, Kochenderfer and Ladd (1996) found no relation between being bullied and subsequent academic achievement in their study of students assessed in the fall and spring of kindergarten, nor did Rueger and Jenkins (2014) in their study of seventh and eighth graders assessed in the fall and spring of one academic year. Feldman and colleagues (2014) also reported no association between being a target of bullying and academic achievement in their 5-year longitudinal study of youth ages 11-14. Poor academic performance can also be a predictor of peer victimization ( Vaillancourt et al., 2013b ). The authors found that poor writing performance in third grade predicted increased bullying behavior in fifth grade that was stable until the end of eighth grade.

The longitudinal associations between peer victimization and school attendance are also equivocal, with some showing positive associations ( Baly et al., 2014 ; Buhs et al., 2006 ; Gastic, 2008 ; Kochenderfer and Ladd, 1996 ; Smith et al., 2004 ) and others not finding a statistically significant association ( Forero et al., 1999 ; Glew et al., 2008 ; Rueger et al., 2011 ; Vaillancourt et al., 2013b ). 10

In summary, there have been a number of cross-sectional and longitudinal studies that have provided support for a relation between being bullied and increased risk for poor academic achievement. However, given the inconsistent results found with longitudinal studies, more research is warranted in this area to more fully ascertain the relation between being bullied and academic achievement over time.

• CONSEQUENCES FOR INDIVIDUALS WHO BULLY

There is evidence that supports a finding that individuals who bully others have contradictory attributes ( Institute of Medicine and National Research Council, 2014a ; Vaillancourt et al., 2010b ). Research suggests that there are children and adolescents who bully others because they have some form of maladjustment ( Olweus, 1993a ) or, as mentioned in Chapter 3 , are motivated by establishing their status in a social network ( Faris and Ennett, 2012 ; Rodkin et al., 2015 ; Sijtsema et al., 2009 ; Vaillancourt et al., 2003 ). Consequently, the relation between bullying, being bullied, acceptance, and rejection is complex ( Veenstra et al., 2010 ). This complexity is also linked to a stereotype held by the general public about individuals who bully. This stereotype casts children and youth who bully others as being high on psychopathology, low on social skills, and possessing few assets and competencies that the peer group values ( Vaillancourt et al., 2010b ). Although some occurrence of this “stereotypical bully” or “classic bully” is supported by research ( Kumpulainen et al., 2001 ; Olweus, 1993a ; Sourander et al., 2007 ), when researchers consider social status in relation to perpetration of bullying behavior, a different profile emerges. These studies suggest that most children and youth who bully others wield considerable power within their peer network and that high-status perpetrators tend to be perceived by peers as being popular, socially skilled, and leaders ( de Bruyn et al., 2010 ; Dijkstra et al., 2008 ; Peeters et al., 2010 ; Thunfors and Cornell, 2008 ; Vaillancourt et al., 2003 ). High-status bullies have also been found to rank high on assets and competencies that the peer group values such as being attractive or being good athletes ( Farmer et al., 2003 ; Vaillancourt et al., 2003 ); they have also been found to rank low on psychopathology and to use aggression instrumentally to achieve and maintain hegemony (for reviews, see Rodkin et al., 2015 , and Vaillancourt et al., 2010b ). Considering these findings of contrasting characteristics of perpetrators of bullying behavior, it makes sense that the research on outcomes of perpetrating is mixed. Unfortunately, most research on the short- and long-term outcomes of perpetrating bullying behavior has not taken into account this heterogeneity when considering the impact to children and youth who have bullied their peers.

Psychosomatic Consequences

Findings from cross-sectional studies that reported data on individuals who bullied others have shown that these individuals are at risk of developing psychosomatic problems ( Gini, 2008 ; Srabstein et al., 2006 ). Gini and Pozzoli (2009) conducted a meta-analysis to test whether children involved in bullying behavior in any role are at risk for psychosomatic problems. They included studies ( n = 11) that examined the association between bullying involvement and psychosomatic complaints in children and adolescents between the ages of 7 and 16. The studies included in the meta-analysis used self-report questionnaires; reports from peers, parents, or teachers; and clinical interviews that resulted in a clinical rating of the subject's behaviors and health problems. The included studies also had enough information to calculate effect sizes. An analysis of six studies that met the selection criteria revealed that children who bully had a higher risk ( OR = 1.65, 95% CI [1.34, 2.04]) of exhibiting psychosomatic problems than their uninvolved peers.

This meta-analysis was limited because of its inclusion of cross-sectional and observational studies. Such studies do not allow firm conclusions on cause and effect; hence, the association between bullying perpetration and psychosomatic problems may be difficult to interpret. The methodologies used in the studies make them susceptible to bias and misclassification due to the reluctance of individuals who bully to identify themselves as perpetrators of bullying behavior. Also, the different forms of victimization included in the underlying studies were not reported in this meta-analysis. Additional research is needed to examine the involvement in perpetrating bullying behavior and its short- and long-term psychosomatic consequences.

Psychotic Problems

Using a population-based cohort study, Wolke and colleagues (2014) examined whether bullying perpetration and being a target of bullying in elementary school predicted psychotic experiences 11 in adolescence. The authors assessed 4,720 individuals between the ages of 8 and 11 who were involved in bullying either as perpetrators or targets. At age 18, suspected or definite psychotic experiences were assessed using semistructured interviews. After controlling for the child's gender, intelligence quotient at age 8, and childhood behavioral and emotional problems, the researchers found that both individuals who are bullied (child report at age 10: OR = 2.4, 95% CI [1.6, 3.4]; mother report: OR = 1.6, 95% CI [1.1, 2.3]) and individuals who bullied others (child report at age 10: OR = 4.9, 95% CI [1.3, 17.7]; mother report: OR = 1.2, 95% CI [0.46, 3.1]) had a higher prevalence of psychotic experiences at age 18. The authors concluded that “involvement in any role in bullying may increase the risk of developing psychotic experiences in adolescence” ( Wolke et al., 2014 , p. 2208).

In summary, several studies have focused on the consequences of bullying for individuals who are bullied and have also reported more broadly on consequences for perpetrators of aggressive behavior (see Gini and Pozzoli, 2009 ; Lereya et al., 2015 ; Reijntjes et al., 2010 ; Ttofi et al., 2011 ), but the consequences of bullying involvement for individuals who perpetrate bullying behavior have been rarely studied to date. That is, although there is a rich literature on aggressors and the outcomes of being aggressive, there are few studies examining bullying perpetration specifically, taking into account the power imbalance, repetition, and intentionality that differentiates aggression from bullying from other forms of peer aggression. As discussed in Chapter 2 , the available research on the prevalence of bullying behavior focuses almost entirely on the children who are bullied. More research, in particular longitudinal research, is needed to understand the short- and long-term physical health, psychosocial, and academic consequences of bullying involvement on the individuals who have a pattern of bullying others, when those individuals are distinguished from children who engage in general aggressive behavior.

• CONSEQUENCES FOR INDIVIDUALS WHO BULLY AND ARE ALSO BULLIED

Individuals who bully and are also bullied experience a particular combination of consequences that both children who are only perpetrators and children who are only targets also experience, such as comorbidity of both externalizing and internalizing problems, negative perception of self and others, poor social skills, and rejection by the peer group. However, at the same time this combination of roles in bullying is negatively influenced by the peers with whom they are interacting ( Cook et al., 2010 ). After controlling for adjustment problems existing prior to incidents of bullying others or being bullied, a nationally representative cohort study found that young children who have been both perpetrators and targets of bullying tended to develop more pervasive and severe psychological and behavioral outcomes than individuals who were only bullied ( Arseneault et al., 2006 ).

Adolescents who were involved in cyberbullying as both perpetrators and targets have been found to be most at risk for negative mental and physical health consequences, compared to those who were only perpetrators, those who were only targets, or those who only witnessed bullying ( Kowalski and Limber, 2013 ; Nixon, 2014 ). For example, the results from a study by Kowalski and Limber (2013) that examined the relation between children's and adolescents' experiences with cyberbullying or traditional bullying and outcomes of psychological health, physical health, and academic performance showed that students who were both perpetrators and targets had the most negative scores on most measures of psychological health, physical health, and academic performance, when compared to those who were only perpetrators, only targets, or only witnesses of bullying incidents.

Wolke and colleagues (2001) examined the association of direct and relational bullying experience with common health problems and found that students ages 6-9 who bullied others and were also bullied by others had more physical health symptoms than children who were only perpetrators or were not involved in bullying behavior. Hunter and colleagues (2014) evaluated whether adolescents who were involved in bullying experienced sleep difficulties more than adolescents who were not involved. They analyzed surveys that were originally collected on behalf of the UK National Health Service and had been completed by adolescents ages 11-17. Controlling for gender, school-stage, socioeconomic status, ethnicity, and other factors known to be associated with sleep difficulties—alcohol consumption, tea or coffee consumption, and illegal drug use—the authors found that individuals who were both perpetrators and targets in bullying incidents were almost three times more likely ( OR = 2.90, 95% CI [1.17, 4.92]) to experience these sleep difficulties, compared to uninvolved young people. Additional research is needed to identify the mechanisms underlying short- and long-term physical health outcomes of individuals who bully and are also bullied.

There is evidence that individuals who are both perpetrators and targets of bullying have the poorest psychosocial profile among individuals with any involvement in bullying behavior; their psychosocial maladjustment, peer relationships, and health problems are similar to individuals who are only bullied, while their school bonding and substance use is similar to individuals who are only perpetrators ( Graham et al., 2006 ; Nansel et al., 2001 , 2004 ). Individuals who both bully and are also bullied by others experience a greater variety of both internalizing and externalizing symptoms than those who only bully or those who are only bullied ( Kim et al., 2006 ).

Some meta-analyses have examined the association between involvement in bullying and internalizing problems in the school-age population and concluded that that individuals who are both perpetrators and targets of bullying had a significantly higher risk for psychosomatic problems than individuals who were only perpetrators or who were only targets ( Gini and Pozzoli, 2009 ; Reijntjes et al., 2010 ). In their meta-analysis, Gini and Pozzoli (2009) reviewed studies that examined the association between involvement in bullying and psychosomatic complaints in children and adolescents. Analysis of a subgroup of studies ( N = 5) that reported analyses for individuals who bully and are also bullied by others showed that these individuals have a significantly higher risk for psychosomatic problems than uninvolved peers ( OR = 2.22, 95% CI [1.77, 2.77]).

Studies suggest that individuals who bully and who are also bullied by others are especially at risk for suicidal ideation and behavior, due to increased mental health problems (see Holt et al., 2015 , and Box 4-1 ).

Suicidality: A Summary of the Available Meta-Analyses.

Similar to individuals who bully, individuals who bully and are also bullied by others often demonstrate heightened aggression compared with non-involved peers. Compared to these other groups, they are by far the most socially ostracized by their peers, most likely to display conduct problems, and least engaged in school, compared with those who are either just perpetrators or just targets; they also report elevated levels of depression and loneliness ( Juvonen et al., 2003 ). Additional research is needed that examines the unique consequences of those children and youth characterized as “bully-victims” because often they are not separated out from “pure victims” (those who are bullied only) in studies. School shootings are a violent externalizing behavior that has been associated with consequences of bullying behavior in the popular media (see Box 4-2 for additional detail).

Bullying and School Shootings.

Several studies have examined the associations between bullying involvement in adolescence and mental health problems in adulthood and have found that individuals who have bullied others and have also been bullied had increased risk of high levels of critical symptoms of psychosis compared to non-involved peers ( Gini, 2008 ; Sigurdson et al., 2015 ). Research is limited in this area, and the topic warrants further investigation.

• CONSEQUENCES OF BULLYING FOR BYSTANDERS

Bullying cannot be viewed as an isolated phenomenon; it is intertwined within the particular peer ecology that emerges, an ecology constituted of social processes that serve particular functions for the individual and for the group ( Rodkin, 2004 ). Bullying frequently occurs in the presence of children and youth who are bystanders or witnesses. Research indicates that bullying can have significant adverse effects on these bystanders ( Polanin et al., 2012 ).

Bystanders have reported feelings of anxiety and insecurity ( Rigby and Slee, 1993 ) which stemmed, in part, from fears of retaliation ( Musher-Eizenman et al., 2004 ) and which often prevented bystanders from seeking help ( Unnever and Cornell, 2003 ). In a study to explore the impact of bullying on the mental health of students who witness it, Rivers and colleagues (2009) surveyed 2,002 students, ages 12-16 and attending 14 schools in the United Kingdom, using a questionnaire that included measures of bullying at school, substance abuse, and mental health risk. They found that witnessing bullying significantly predicted elevated mental health risks even after controlling for the effect of also being a perpetrator or victim (range of = .07 to .15). They also found that being a witness to the bullying predicted elevated levels (= .06) of substance use. Rivers and Noret (2013) found that, compared to students who were not involved in bullying, those who observed bullying reported more symptoms of interpersonal sensitivity (e.g., feelings of being hurt or inferior), helplessness, and potential suicide ideation.

In conclusion, there is very limited research available on the consequences of witnessing bullying for those children and youth who are the bystanders. Studies of bystander behavior have traditionally sought to understand their motives for participation in bullying ( Salmivalli, 2010 ), their roles ( Lodge and Frydenberg, 2005 ; Salmivalli et al., 1996 ), their behavior (either reinforcing the bully or defending the victim) in bullying situations ( Salmivalli et al., 2011 ), and why observers intervene or do not intervene ( Thornberg et al., 2012 ) from a social dynamic perspective, without exploring the emotional and psychological impact of witnessing bullying. More research is needed to understand these consequences.

MULTIPLE EXPOSURES TO VIOLENCE 12

One subpopulation of school-aged youth that may be at increased risk for detrimental short- and long-term outcomes associated with bullying victimization is poly-victims. Finkelhor and colleagues (2007) coined the terms “poly-victim” and “poly-victimization” to represent a subset of youth who experience multiple victimizations of different kinds—such as exposure to (1) violent and property crimes (e.g., assault, sexual assault, theft, burglary), (2) child welfare violations (child abuse, family abduction), (3) the violence of warfare and civil disturbances, and (4) being targets of bullying behavior—and who manifest high levels of traumatic symptomatology. The identification of a poly-victim is grounded not only in the frequency of the victimization but also in victimization across multiple contexts and perpetrators ( Finkelhor et al., 2007 , 2009 ).

Ford and colleagues (2010) determined that poly-victims were more likely to meet criteria for psychiatric disorder, including being two times more likely to report depressive symptoms, three times more likely to report posttraumatic stress disorder, up to five times more likely to use alcohol or drugs, and up to eight times more likely to have comorbid disorders, compared to youth that did not meet criteria for poly-victimization. Poly-victims often engaged in delinquent behavior, associated with deviant peers ( Ford et al., 2010 ), and were entrenched within the juvenile justice system ( Ford et al., 2013 ). Students who were poly-victims in the juvenile justice system reported higher levels of traumatic symptomatology ( Finkelhor et al., 2005 ). However, it is currently unclear whether being bullied plays a major or minor role in poly-victimization.

• MECHANISMS FOR THE PSYCHOLOGICAL EFFECTS OF BULLYING

In the following sections, the committee describes five potential mechanisms for the psychological effects of bullying behavior for both the children who are bullied and children who bully. These include self-blame, social cognition, emotional dysregulation, genetic predisposition to mental health outcomes and bullying, and telomere erosion. 13

One important mechanism for the psychological effects of bullying is how the targets of bullying construe the reason for their plight ( Graham, 2006 ). For example, a history of bullying and the perception of being singled out as a target might lead an individual to ask “Why me ?” In the absence of disconfirming evidence, some might come to blame themselves for their peer relationship problems. Self-blame and accompanying negative affect can then lead to many negative outcomes, including low self-esteem, anxiety, and depression ( Graham and Juvonen, 1998 ).

The adult rape literature (another form of victimization) highlights a correlation between experiencing rape and self-attributions that imply personal deservingness, labeled characterological self-blame, since they may lead to the person thinking of themselves as chronic victims ( Janoff-Bulman, 1979 ). From an attributional perspective, characterological self-blame is internal and therefore reflects on the self; it is stable and therefore leads to an expectation that harassment will be chronic; and it is uncontrollable, suggesting an inability to prevent future harassment. Attributing negative outcomes to internal, stable, and uncontrollable causes leads individuals to feel both hopeless and helpless ( Weiner, 1986 ). In contrast, behavioral self-blame (e.g., “I was in the wrong place at the wrong time”) implies a cause that is both unstable (the harassment is not expected to occur again) and controllable (there are responses in one's repertoire to prevent future harassment). Several researchers in the adult literature have documented that individuals who make characterological self-blaming attributions for negative outcomes cope more poorly, feel worse about themselves, and are more depressed than individuals who make attributions to their behavior (see Anderson et al., 1994 ). Research with early adolescents also revealed that characterological self-blame for academic and social failure resulted in heightened depression ( Cole et al., 1996 ; Tilghman-Osborne et al., 2008 ).

In the first attribution study focused specifically on bullying, Graham and Juvonen (1998) documented that sixth grade students with reputations as targets made more characterological self-blaming attributions for harassment than behavioral self-blaming attributions. Characterological self-blame, in turn, partly mediated the relationship between victim status and psychological maladjustment as measured by depression and social anxiety. Many studies since then have documented the relation between being targets of bullying, characterological self-blame, and maladjustment ( Graham et al., 2006 , 2009 ; Perren et al., 2012 ; Prinstein et al., 2005 ). Furthermore, bullied youth who endorsed characterological self-blame were likely to develop negative expectations about the future, which may also increase risk for continued bullying. For example, Schacter and colleagues (2014) reported that characterological self-blame endorsed in the fall of sixth grade predicted increases in reports of being bullied in the spring of sixth grade. Self-blame can then instigate psychological distress over time as well as increases in experiences of being bullied.

Such findings have implications for interventions targeted at bullied youth. The goal would be to change targets' maladaptive thoughts about the causes of their plight. For example, one could seek more adaptive attributions that could replace characterological self-blame. In some cases, change efforts might target behavioral explanations for being bullied (e.g., “I was in the wrong place at the wrong time”). In such cases, the goal would be to help targeted youth recognize that they have responses in their repertoire to prevent future encounters with harassing peers—that is, the cause is unstable and controllable ( Graham and Bellmore, 2007 ). External attributions also can be adaptive because they protect self-esteem ( Weiner, 1986 ). Knowing that others are also victims or that there are some aggressive youth who randomly single out unsuspecting targets can help lessen the tendency to self-blame ( Graham and Bellmore, 2007 ; Nishina and Juvonen, 2005 ). This approach of altering dysfunctional thoughts about oneself to produce changes in affect and behavior has produced a rich empirical literature on attribution therapy in educational and clinical settings (see Wilson et al., 2002 ). The guiding assumption of that research can be applied to alleviating the plight of targets of bullying.

Social Cognition

The most commonly cited models of social cognitive processes often connect back to work by Bandura (1973) , as well as to more recent conceptualizations by Crick and Dodge (1994) . These models have been applied to understanding aggressive behavior, but there has been less research applying these models to bullying behavior specifically. Related research by Anderson and Bushman (2002) on their general aggression model allows for a more focused understanding of the thoughts, feelings, and behaviors that contribute to the development of the negative outcome. This framework characterizes the inputs, the routes, the proximal processes, and the outcomes associated with aggressive behavior and either being targeted by or perpetrating bullying behavior ( Kowalski and Limber, 2013 ; Vannucci et al., 2012 ). Although these theories pertain to aggressive behavior more broadly, given that bullying is considered by most researchers to be a specific form of aggressive behavior, these broader theories may also improve understanding of the etiology and development of bullying. For example, research on hostile attribution bias suggests that aggressive youth are particularly sensitive to ambiguous and potentially hostile peer behaviors. Similar hypersensitivity to threat is also likely present in youth who bully.

Another particular element of social cognitive processes that has been linked with aggressive behavior is normative beliefs about aggressive retaliation ( Crick and Dodge, 1994 ; Huesmann and Guerra, 1997 ). Such beliefs include the belief that aggressive retaliation is normative, acceptable, or justified, given the context of provocation. There has been exploration of links between these beliefs and both reactive and proactive aggression. However, there has been relatively limited research specifically focused on bullying behavior. Yet, the available literature suggests that although it may seem as if targets of bullying would most likely endorse such attitudes, it is the perpetrators of bullying, including those who are involved in bullying as both a perpetrator and a target, who are mostly likely to support aggressive retaliation ( Bradshaw et al., 2009 , 2013 ; O'Brennan et al., 2009 ).

Emotion Dysregulation

Attempts to identify mechanisms linking bullying to adverse outcomes have largely focused on social-cognitive processes ( Dodge et al., 1990 ) as described above. More recently, researchers have begun to examine emotion dysregulation as an additional mechanism that explains associations between peer victimization and adverse outcomes. Emotion regulation refers to the strategies that people use to “increase, maintain, or decrease one or more components of an emotional response” ( Gross, 2001 , p. 215). One's choices among such strategies have implications not only for how robustly one responds to a stressor but also for how quickly one can recover from a stressful experience. Several studies have shown that emotion regulation difficulties—also called emotion dysregulation —increase youths' risk of exposure to peer victimization ( Hanish et al., 2004 14 ) and to bullying ( Mahady Wilton et al., 2000 ). However, it is important to understand whether peer victimization itself causes emotion regulation difficulties, which in turn predict the adverse outcomes that result from peer victimization (e.g., depression, aggressive behaviors).

Several lines of evidence support the hypothesis that emotion dysregulation may account for the relationship between peer victimization and adverse outcomes among adolescents. First, constructs that are related to peer victimization—including social exclusion ( Baumeister et al., 2005 ) and stigma ( Inzlicht et al., 2006 )—impair self-regulation. Second, chronic stress during childhood and adolescence leads to deficits in emotion regulation ( Repetti et al., 2002 ). Bullying has been conceptualized as a chronic stressor for children who are the perpetrators and the targets ( Swearer and Hymel, 2015 ), which in turn may disrupt emotion regulation processes. Third, laboratory-based studies have indicated that peer victimization is associated with emotion dysregulation (e.g., self-directed negative emotion, emotional arousal and reactivity) in the context of a novel peer interaction ( Rudolph et al., 2009 ) and in a contrived play-group procedure ( Schwartz et al., 1993 ). Over time, the effort required to manage the increased arousal and negative affect associated with peer victimization 15 may eventually diminish individuals' coping resources and therefore their ability to understand and adaptively manage their emotions, leaving them more vulnerable to adverse outcomes ( McLaughlin et al., 2009 ).

Several studies have provided empirical support for emotion dysregulation as a mediator of the association between peer victimization and adverse outcomes among adolescents. In one of the first longitudinal demonstrations of mediation, McLaughlin and colleagues (2009) , using data from a large, prospective study of adolescents (ages 11-14), showed that peer victimization at baseline predicted increases in emotion dysregulation four months later, controlling for initial levels of emotion dysregulation. In turn, emotion dysregulation predicted subsequent psychological distress (depressive and anxious symptoms), thereby mediating the prospective relationship between peer victimization (relational and reputational forms) and internalizing symptoms ( McLaughlin et al., 2009 ). Subsequent research from this same sample of adolescents showed that emotion dysregulation also mediated the prospective relationship between peer victimization and subsequent aggressive behavior ( Herts et al., 2012 ).

There is also emerging evidence that emotion regulation mediates relationships between bullying and adverse outcomes. In one example of this work, Cosma et al. (2012) examined associations between bullying and several emotion regulation strategies, including rumination, catastrophizing, and other-blaming, in a sample of adolescents. Although bullying was predictive for each of these emotion regulation strategies, only one (catastrophizing) mediated the relationship between being a target of bullying and subsequent emotional problems. Thus, while more research is needed, existing evidence suggests that both social-cognitive and emotion regulation processes may be important targets for preventive interventions among youths exposed to peer victimization and bullying.

Genetic Predisposition to Mental Health Outcomes and Bullying

Longitudinal research suggests that being the victim or perpetrator of bullying does not lead to the same pathological or nonpathological outcomes in every person ( McDougall and Vaillancourt, 2015 ). There are many factors that contribute to how a person responds to the experience of being victimized, with very strong links already established with life experiences, as reviewed above. Most studies examining heterogeneity in outcomes associated with bullying have focused on environmental characteristics, such as individual, family, and school-level features to explain why some individuals fare better or worse when involved with bullying ( Vaillancourt et al., in press ). For example, the moderating role of the family has been examined with results indicating that bullied children and youth with better home environments tend to fare better than those living with more complicated families ( Flouri and Buchanan, 2003 ; also see Chapter 3 of this report). Far fewer studies have examined the role of potential genetic influences as mediators between life experiences such as bullying and mental health outcomes. Identifying potential genetic influences is critical for improving understanding of the rich behavioral and epidemiological data already gathered. At the present time, evidence-based understanding of physiology and neuroscience is very limited, and insufficient data have been gathered to produce informed hypothesis testing.

There is a growing body of literature examining the relative role of genes' interaction with the environment in relation to experiences with trauma. However, there are fewer studies exploring potential relations between genes and being the target or perpetrator of bullying. At first glance these studies may appear to suggest that a person's involvement with bullying is predetermined based on his/her genetic profile. Yet, it is important to bear in mind that heritable factors are also associated with specific environments—meaning it is difficult to separate genetic effects from environmental effects. This is a phenomenon termed gene-environment correlations , abbreviated as rGE ( Brendgen, 2012 ; Plomin et al., 1977 ; Scarr and McCartney, 1983 ). For example, aggression, which is highly heritable ( Niv et al., 2013 ), can be linked to the selection of environments in different ways (for review, see Brendgen, 2012 ). Aggressive children may choose friends who are similar in their genetically influenced behavioral characteristic of being aggressive, and this type of selection influences the characteristics of their peer group ( Brendgen, 2012 , p. 420). This is an example of selective rGE. A child's genetically influenced characteristic to be aggressive can also produce a negative reaction from others, such as being disliked. This environmental variable of being rejected now “becomes correlated with the aggressive genotype” ( Brendgen, 2012 , p. 421). This is an example of evocative rGE. Another way that a person's genetic predisposition can be correlated with their environment is through a more passive process, called a passive rGE ( Brendgen, 2012 ). For example, aggressive parents may be more likely to live in high-crime neighborhoods, which influence the probability that their child will be associating with antisocial peers. These important rGE processes and confounds of interaction notwithstanding, it is worth mentioning that the research on the genetics of being a target or perpetrator of bullying is still in its infancy, and caution is needed when evaluating the results, as replication is much needed in this area. Before considering these studies, the committee first reviews the concept of how genetic differences influence behavior because it is important to clarify new concepts in this burgeoning area of science (see Box 4-3 ).

How Do Genes Influence Behavior?

With this backdrop in mind, the committee focused on twin studies of familial (family environment) versus genetic influence, gene by environment interaction, and a newer area of inquiry, epigenetics: the study of cellular and physiological phenotypic trait variations caused by external or environmental factors.

Twin Studies

Twin studies are routinely used to examine the relative influence of genetics and the environment on a particular phenomenon, such as being the target or perpetrator of bullying. In these studies, the causes of phenotypic variation (for example the variation in being a target or perpetrator of bullying) is separated into three components: (1) the additive genetic component or the heritable factor; (2) the shared environment component or the aspect of the environment twins share such as poor family functioning; and (3) the nonshared environment component or the aspect of the environment that is unique to each twin, such as the classroom if twins are in different classes.

Studies that decompose the unique effects of the environment and genetics on bullying behavior are best illustrated by two examples. Using data from the Environmental Risk (E-Risk) Longitudinal Twin Study, a study of high-risk 16 British twins reared together and apart, Ball and colleagues (2008) examined children's involvement in bullying and the genetic versus environmental contributions associated with their involvement. The twins in this study were assessed at ages 7 and 10 on their experiences with bullying, using teacher and parent reports. Results indicated that 73 percent of the variation in being the target of bullying and 61 percent of the variation in bullying perpetration were accounted for by genetic factors. In another study of Canadian twins reared together and assessed at age 7, using teacher and peer reports to assess peer victimization and aggression, Brendgen and colleagues (2008) found that for girls, 60 percent of the variation in aggression was accounted for by genetic factors and for boys, the variation estimate was 66 percent. For peer victimization, the Canadian study found that genetics did not play a role in the prediction of being targeted by peers. In fact, almost all of the variance was accounted for by environmental factors—29 percent of the variance in peer victimization was from the shared environment and 71 percent from the nonshared environment. The authors concluded that “genetic modeling showed that peer victimization is an environmentally driven variable that is unrelated to children's genetic disposition” ( Brendgen et al., 2008 , p. 455).

These two studies address the role genetics might play in the expression of aggressive behavior but conflict on the heritability of being a target of bullying. Most studies examining the heritability of externalizing problems, which includes studies on perpetrating aggression and bullying, report high heritability estimates. In fact, a recent meta-analysis found that aggression and rule-breaking were highly influenced by genetics, estimating the heritability rate at 41 percent ( Niv et al., 2013 ). Moreover, studies have found that the heritability estimates tend to be higher for more serious forms of antisocial behavior. For example, the heritability of psychopathy in 7-year-old British twin children reared together and apart and studied in the Twins Early Development Study was reported to be 81 percent ( Viding et al., 2005 ). However, estimates of the heritability of peer victimization vary across studies, as illustrated by the above results from Ball and colleagues (2008) contrasted with those from Brendgen and colleagues (2008) , and even within studies ( Brendgen et al., 2008 , 2013 ).

Brendgen and colleagues have since revised their assessment about the role genetics play in the prediction of being the target of bullying. In a more recent study, following the same children highlighted in the 2008 paper ( Brendgen et al., 2008 ) across three assessment periods (kindergarten, grade 1, and grade 4), Boivin and colleagues (2013) reported that at each grade, among twins who were reared together and apart, genetic factors accounted for a notable percentage of the variance in children's difficulties with peers. Peer difficulties were assessed as a latent factor derived from self-, teacher-, and peer-reports of peer victimization 17 and peer rejection. Specifically, in kindergarten and grade 1, 73 percent of the variance was accounted by genetic factors and in grade 4, genetic factors account for 94 percent of the variance in peer rejection and victimization.

There are several reasons for discrepancies between and within studies of the genetic contribution to bullying behavior. One reason is related to how peer victimization is assessed. Parent-, teacher-, peer-, and self-reports of bullying victimization have been shown to vary considerably across reporters ( Ostrov and Kamper, 2015 ; Patton et al., 2015 ; Shakoor et al., 2011 ); thus, the method used to assess involvement with bullying may lead to different results. Another reason for the differences may be related to development. The influence of the environment is expected to change as children age. Young children are particularly sensitive to family influences, while the influence of peers tends to matter more during adolescence ( Harris, 1995 ). Moreover, the type of environment a person is exposed to (i.e., harsh or nurturing) interacts with genes to produce a brain that is tailored to deal with the particular demands of that environment.

Taken together, the genetic studies reviewed suggest that aggression, which characterizes the perpetrator role in bullying ( Vaillancourt et al., 2008 ), might have heritable components, but the findings on being the target of bullying or other aggressive behavior are mixed. Thus, the role of genetic influences on both perpetrating and being a target of bullying requires more empirical attention before conclusions can be drawn.

Gene-by-Environment Interactions

Researchers also question whether specific genotypic markers of vulnerability (e.g., candidate genes) influence developmental outcomes in the face of adversity (i.e., environment). Importantly, there is some indication that genetics influences the mental health issues related to bullying highlighted above, such as depression and heightened aggression. For example, in gene-environment studies, candidate genes have been examined as moderators of the exposure to a toxic stressor such as child maltreatment and health outcomes such as depression. When the body experiences repeated bouts of stress that fail to resolve quickly, the heightened state of vigilance and preparedness depletes it of resources and the stress hormone cortisol begins to produce adverse effects. Specifically, prolonged stress disrupts brain functions and results in compromised decision making, faulty cognitive assessment, compromised learning and memory, and a heightened sense of threat that alters behavior ( Lupien et al., 2005 ; McEwen, 2014 ). There is evidence that the impact of changes in cortisol (either too high or too low) on learning may contribute, in part, to bullied children's decline in academic performance ( Vaillancourt et al., 2011 ), overeating/metabolic disorder, or emotional dysregulation, but this research is relatively new and needs to be explicitly explored within the context of bullying ( McEwen, 2014 ).

A paradigmatic example of this type of study is one by Caspi and colleagues (2003) , in which the moderating role of a functional polymorphism in the promoter region of the serotonin transporter gene 5-HTTLPR was examined in relation to exposure to maltreatment in childhood and depression in adulthood. Results indicated that depression rates were far greater among abused individuals if they had two copies of the short allele. 18 Among individuals with a long allele, depression rates were lower, suggesting that the long allele was protective, while the short allele was a risk factor for depression in the face of adversity. Although the exact role of this serotonin-related gene has been a subject of controversy, a meta-analysis concluded that overall, the results are consistent across studies ( Karg et al., 2011 ). Nevertheless, skepticism and controversy remain regarding studies of gene-environment interactions ( Dick et al., 2015 ; Duncan, 2013 ; Duncan and Keller, 2011 ; Duncan et al., 2014 ). This important debate notwithstanding, there is evidence that variations in genotype might moderate the relation between exposure to being bullied and health outcomes. For example, Sugden and colleagues (2010) found that bullied children who carried two short versions of the 5-HTTLPR gene were more likely to develop emotional problems than bullied children who carried the long allele. Importantly, this moderating effect was present even when pre-victimization emotional problems were accounted for statistically. In addition to this study, three other studies have demonstrated the moderating effect of the 5-HTTLPR gene in the bullying-health link ( Banny et al., 2013 ; Benjet et al., 2010 ; Iyer et al., 2013 ), with depression being worse for carriers of the short/short genotype (both alleles are the short version) than carriers of the short/long and long/long genotypes.

Although the evidence suggests that genotypes moderate the relation between being a target of bullying and poorer mental health functioning like depression, it is important to acknowledge that this relation is more complex. Indeed, some individuals may be particularly biologically sensitive to negative environmental influences such as being bullied, but this genetic vulnerability can also be linked to better outcomes in the context of a more supportive and enriched environment (see Vaillancourt et al., in press ). This phenomenon is termed differential susceptibility ( Belsky and Pluess, 2009 ; Boyce and Ellis, 2005 ). For example, in their study of 5 and 6-year old children, Obradovic and colleagues (2010) found that high stress reactivity as measured using respiratory sinus arrhythmia and salivary cortisol was linked to poorer socioemotional behavior in the context of being in an environment that was high in family adversity. In a context characterized by lower adversity, high stress-reactive children had more adaptive outcomes.

To the committee's knowledge, there are no studies that have examined bullying perpetration in relation to serotonin transporter polymorphisms, although there are studies that have examined this polymorphism in aggressive and non-aggressive children. For example, Beitchman et al. (2006) examined 5-HTTLPR in clinically referred children between the ages of 5 and 15 and found a positive association between the short/short genotype and aggression. In other studies, the short allele has been associated with problems with impulse control that includes the use of aggression ( Retz et al., 2004 ).

The moderating role of different candidate genes has also been examined in relation to exposure to childhood adversity and poorer developmental outcomes (see review by Vaillancourt et al., in press ). With respect to bullying, only a few studies have examined gene-environment interactions. In one study by Whelan and colleagues (2014) , harsh parenting was associated with increased peer victimization and perpetration, but this effect was not moderated by the Monoamine Oxidase A (MAOA) genotype. 19 In another longitudinal study, Kretschmer and colleagues (2013) found that carriers of the 4-repeat homozygous variant of the dopamine receptor D4 gene were more susceptible to the effects of peer victimization 20 on delinquency later in adolescence than noncarriers of this allele. Finally, in a large sample of post-institutionalized children from 25 countries, VanZomeren-Dohm and colleagues (2015) examined the moderating role of FKBP5 rs1360780 21 in the relation between peer victimization 22 and depression symptoms. In this study, gender was also found to be a moderator. Specifically, girls who had the minor genotype (TT or CT) were more depressed at higher levels of peer victimization, but less depressed at lower level of peer victimization than girls who had CC genotype. For boys, the CC genotype was associated with more symptoms of depression than girls with the same CC genotype who had been bullied.

It is clear that genetics influences how experiences contribute to mental and physical well-being, although the specifics of these gene-environment interactions are complex and not completely understood. Even though genes appear to modulate humans' response to being a target or a perpetrator of bullying behavior, it is still unclear what aspects of these experiences are interacting with genes and which genes are implicated to produce the variability in outcomes. Human genes and environment interact in a very complex manner: what biological events a particular gene influences can change at different stages of development. That gene therefore interacts with the environment in unique ways across the development timeline. These gene-environment interactions can be subtle and are under constant flux ( Lake and Chan, 2015 ). Knowing both the genes involved and the specific environment conditions is critically important to understanding these interactions; a simplistic view of either the genetic or environmental component, especially when considered in isolation from the behavioral literature, is unlikely to be productive.

Epigenetic Consequences

It is clear from the research reviewed here that there are a variety of pathways leading to adaptive and maladaptive endpoints and that these pathways can also vary within the “system” along with other conditions and attributes ( McDougall and Vaillancourt, 2015 , p. 300), including a person's genetic susceptibility. In this section, the committee focuses on studies examining how genetic susceptibility can make certain individuals more sensitive to negative environmental influences.

Although a person's DNA is fixed at conception (i.e., nonmalleable), environment can have a strong effect on how some genes are used at each of the stages of development. One way such changes in gene use and expression can occur is through an epigenetic effect, in which environmental events alter the portions of the genome that control when gene replication is turned on or off and what parts of a gene get transcribed ( McGowan et al., 2009 ; Roth, 2014 ). That is, while an individual's genetic information is critically important, the environment can help to increase or decrease how some genetic information is used by indirectly turning on or off some genes based on input received by somatic cells from the environment. Such epigenetic alterations have been empirically validated in several animal studies. For example, in one line of epigenetic studies, infant rat pups are raised with either low- or high-nurturing mothers or with mothers that treated the pups harshly. The researchers found that the type of maternal care received in infancy had a notable effect on the rats' subsequent ability to deal with stress ( McGowan et al., 2011 ; Roth and Sweatt, 2011 ; Weaver et al., 2004 ). The behavioral effects were correlated with changes in DNA methylation. 23 Epigenetic changes associated with gene-environment interactions is a new and exciting research area that provide a direct link between how our genes are read and is thought to enable us to pass our experiences to the next generations. It is helpful to think of genes as books in a library and epigenetics as placing a barrier in front of a book to decrease the chances it is read or providing easy access to the book. Thus far, research has found that certain epigenetic mechanisms are strongly correlated with different neurobehavioral developmental trajectories, including changes in vulnerability and resilience to psychopathology. How epigenetics relates to individual responses to being a target or perpetrator of bullying is not clear, but the research in related areas of behavior highlights an important emerging area for investigation.

Various epigenetic processes appear to interact with many changes in the brain produced by early life experiences, including not only the number and shape of brain cells but also how these cells connect to one another at synapses ( Hanson et al., 2015 ).

Regarding bullying, the committee identified only one study that has examined epigenetic changes. Specifically, Ouellet-Morin and colleagues (2013) found an increase in DNA methylation of the serotonin transporter gene for children who had been bullied by their peers but not in children who had not been bullied. These researchers also found that children with higher serotonin DNA methylation had a blunted cortisol response to stress, which they had previously shown changes as a consequence of poor treatment by peers ( Ouellet-Morin et al., 2011 ). That is, their 2011 study of twin children assessed at ages 5 and 10 found that being bullied was correlated with a change in how the body responds to stress. Bullied children displayed a blunted cortisol response to a psychosocial stress test. Because the design of the study involved an examination of identical twins who were discordant with respect to their experiences of being bullied (one twin was bullied while the other one was not), Ouellet-Morin and colleagues (2011) concluded that the effect could not be attributed to “variations in either genetic makeup, family environment, or other concomitant factors, nor could they be attributed to the twins' perceptions of the degree of stress experienced during the task” ( Vaillancourt et al., 2013a , p. 243).

In summary, it is important to note that there is no gene for being a perpetrator or a target of bullying behavior. Based on current knowledge of the genetics of complex social behavior, such as bullying, the genetic component of individual response is likely to involve multiple genes that interact with the environment in a complex manner. The current understanding of genetics and complex behaviors is that genes do not cause a behavior; gene-by-environment studies do not use the word “environment” the same way it is used in everyday language or even in traditional social psychology (as in Chapter 3 ). Rather, it is a construct used in a model to estimate how much variability exists in a given environment. This means that the same gene placed in different environments would yield very different percentages for gene-environment interactions. It is unclear how this information would inform our understanding of bullying.

Telomere Erosion Consequences

Epigenetic research has found that negative life experiences can alter the expression of a gene, which in turn, can confer a risk for poor outcomes. Research also suggests that the experience of being bullied is associated with telomere erosion. The end of each chromatid has been found to shorten as people age; this telomere “tail” also erodes as a function of engaging in unhealthy behavior such as smoking or being obese. Telomere erosion is also associated with certain illnesses such as cancer, diabetes, and heart disease ( Blackburn and Epel, 2012 ; Kiecolt-Glaser et al., 2011 ; Vaillancourt et al., 2013a ). Given these associations, scientists are now examining telomere erosion as a biomarker of stress exposure ( Epel et al., 2004 ), including the stress of being bullied by peers.

A recent longitudinal study by Shalev and colleagues (2013) examined telomere erosion in relation to children's exposure to violence, 24 a significant early-life stressor that is known to have long-term consequences for health. They found that exposure to violence, including being a target of bullying, was associated with telomere erosion for children assessed at age 5 and again at age 10. The sample for this study included 236 children recruited from the Environmental-Risk Longitudinal Twin Study ( Moffitt, 2002 ), 42 percent of whom had one or more exposures to violence. The study found that cumulative exposure to violence 25 is positively associated with accelerated telomere erosion in children, from baseline to follow-up, with potential impact for life-long health ( Shalev et al., 2013 ).

In this chapter, the committee reviewed and critically analyzed the available research on the physical health, psychosocial, and academic achievement consequences for children and youth who are bullied, for those who bully, for those who are both bullied and bullies, and for those who are bystanders to events of bullying. It also examined the potential mediating mechanisms of, and the genetic predisposition to, mental health outcomes associated with childhood and youth experiences of bullying behavior. Most studies are cross-sectional and thus provide only associations suggestive of a possible causal effect. This problem is most acute for studies based on anonymous self-report, in which both the independent variable (experience of bullying in one or more roles) and dependent variables (such as emotional adjustment) are data collected at the same time from sources subject to various forms of bias.

The limited amount of data from longitudinal and experimental research designs limits the ability to draw conclusions with respect to causality. Additional longitudinal studies, for example, could help establish that the negative consequences attributed to bullying were not present before the bullying occurred. But even this does not prove a causal effect, since bullying and the associated impairments might be products of some third factor. Below, the committee summarizes what is known about associations and consequences and identifies key conclusions that can be drawn from this evidence base.

• FINDINGS AND CONCLUSIONS

Finding 4.1: Individuals who both bully and are also bullied by others experience a greater variety of both internalizing and externalizing symptoms than those who only bully or are only bullied. Finding 4.2: Individuals who bully others are likely to experience negative emotional, behavioral, and mental health outcomes, though most research has not distinguished perpetration of bullying from other forms of peer aggression. Finding 4.3: A large body of research indicates that individuals who have been bullied are at increased risk of subsequent mental, emotional, and behavioral problems, especially internalizing problems. Finding 4.4: Studies of bystander behavior in bullying have rarely examined the emotional and psychological impact of witnessing bullying. Finding 4.5: Children and youth who are bullied subsequently experience a range of somatic disturbances. Finding 4.6: Social-cognitive factors (e.g., self-blame) and unsuccessful emotion regulation (i.e., emotion dysregulation) mediate relationships between bullying and adverse outcomes. Finding 4.7: There is evidence that stressful events, such as might occur with experiences of being bullied, alter emotional brain circuits. This potential outcome is critically in need of further investigation. Finding 4.8: Genetics influences how experiences contribute to mental and physical well-being, although the nature of this relationship is complex and not completely understood. Finding 4.9: Emerging evidence suggests that repeated exposure to bullying may produce a neural signature that could underlie some of the behavioral outcomes associated with being bullied. Finding 4.10: There are limited data on the physical health consequence of bullying for those individuals who are involved in bullying as targets, perpetrators, as both targets and perpetrators, and as bystanders. Finding 4.11: Poly-victims (individuals who are targets of multiple types of aggression) are more likely to experience negative emotional, behavioral, and mental health outcomes than individuals targeted with only one form of aggression. Finding 4.12: The long-term consequences of being bullied extend into adulthood and the effects can be more severe than other forms of being maltreated as a child. Finding 4.13: Individuals who are involved in bullying (as perpetrators, targets, or both) in any capacity are significantly more likely to contemplate or attempt suicide, compared to children who are not involved in bullying. It is not known whether bystanders are at increased risk of suicidal ideation or suicide attempts. Finding 4.14: There is not enough evidence to date to conclude that being the target of bullying is a causal factor for multiple-homicide targeted school shootings, nor is there clear evidence on how experience as a target or perpetrator of bullying, or the mental health and behavior issues related to such experiences, contribute to school shootings.

Conclusions

Conclusion 4.1: Further research is needed to obtain more in-depth evidence on the physical health consequences of being the target of bullying including neural consequences. Conclusion 4.2: Additional research is needed to examine mediators of short- and long-term physical health outcomes of individuals who are bullied. Evidence is also needed regarding how these outcomes vary over time for different groups of children and youth, why individuals with similar experiences of being bullied might have different physical health outcomes, and how physical and emotional health outcomes intersect over time. Conclusion 4.3: Although the effects of being bullied on the brain are not yet fully understood, there are changes in the stress response systems and in the brain that are associated with increased risk for mental health problems, cognitive function, self-regulation, and other physical health problems. Conclusion 4.4: Bullying has significant short- and long-term internalizing and externalizing psychological consequences for the children who are involved in bullying behavior. Conclusion 4.5: The data are unclear on the role of bullying as one of or a precipitating cause of school shootings. Conclusion 4.6: Individuals who both bully others and are themselves bullied appear to be at greatest risk for poor psychosocial outcomes, compared to those who only bully or are only bullied and to those who are not bullied. Conclusion 4.7: While cross-sectional studies indicate that children who are bullied are at increased risk for poor academic achievement relative to those who are not bullied, the results from longitudinal studies are inconsistent and warrant more research. Conclusion 4.8: Existing evidence suggests that both social-cognitive and emotion regulation processes may mediate the relation between being bullied and adverse mental health outcomes. Conclusion 4.9: Although genes appear to modulate humans' response to being either a target or a perpetrator of bullying behavior, it is still unclear what aspects of these experiences are interacting with genes and which genes are implicated to produce the variability in outcomes. Examining the role of genes in bullying in the context of the environment is essential to providing meaningful information on the genetic component of individual differences in outcomes from being a target or a perpetrator of bullying behavior.

• Anderson CA, Bushman BJ. Human aggression. Annual Review of Psychology. 2002; 53 (1):27–51. [ PubMed : 11752478 ]
• Anderson CA, Miller RS, Riger AL, Dill JC, Sedikides C. Behavioral and characterological attributional styles as predictors of depression and loneliness: Review, refinement, and test. Journal of Personality and Social Psychology. 1994; 66 (3):549–558. [ PubMed : 8169764 ]
• Archer J. Testosterone and human aggression: An evaluation of the challenge hypothesis. Neuroscience and Biobehavioral Reviews. 2004; 30 (3):319–345. [ PubMed : 16483890 ]
• Arseneault L, Walsh E, Trzesniewski K, Newcombe R, Caspi A, Moffitt T. Bullying victimization uniquely contributes to adjustment problems in young children: A nationally representative cohort study. Pediatrics. 2006; 118 (1):130–138. [ PubMed : 16818558 ]
• Baldwin J, Arseneault L, Danese A. Childhood bullying and adiposity in young adulthood: Findings from the E-Risk Longitudinal Twin Study. Psychoneuroendocrinology. 2015; 61 :16.
• Ball HA, Arseneault L, Taylor A, Maughan B, Caspi A, Moffitt TE. Genetic and environmental influences on victims, bullies and bully-victims in childhood. Journal of Child Psychology and Psychiatry. 2008; 49 (1):104–112. [ PubMed : 18181884 ]
• Baly MW, Cornell DG, Lovegrove P. A longitudinal investigation of self- and peer reports of bullying victimization across middle school. Psychology in the Schools. 2014; 51 (3):217–240.
• Bandura A. Aggression: A Social Learning Analysis. Englewood Cliffes, NJ: Prentice-Hall; 1973.
• Banny AM, Cicchetti D, Rogosch FA, Oshri A, Crick NR. Vulnerability to depression: A moderated mediation model of the roles of child maltreatment, peer victimization, and serotonin transporter linked polymorphic region genetic variation among children from low socioeconomic status backgrounds. Development and Psychopathology. 2013; 25 (03):599–614. [ PMC free article : PMC3959105 ] [ PubMed : 23880379 ]
• Baratta MV, Kodandaramaiah SB, Monahan PE, Yao J, Weber MD, Lin PA, Gisabella B, Petrossian N, Amat J, Kim K. Stress enables reinforcement-elicited serotonergic consolidation of fear memory. Biological Psychiatry. 2015; 79 (10):814–822. [ PMC free article : PMC4698247 ] [ PubMed : 26248536 ]
• Barnes DC, Wilson DA. Slow-wave sleep-imposed replay modulates both strength and precision of memory. Journal of Neuroscience. 2014; 34 (15):5134–5142. [ PMC free article : PMC3983797 ] [ PubMed : 24719093 ]
• Barra CB, Silva IN, Rodrigues TMB, Santos JLS, Colosimo EA. Morning serum basal cortisol levels are affected by age and pubertal maturation in school-aged children and adolescents. Hormone Research in Paediatrics. 2015; 83 (1):55–61. [ PubMed : 25592297 ]
• Baumeister RF, DeWall CN, Ciarocco NJ, Twenge JM. Social exclusion impairs self-regulation. Journal of Personality and Social Psychology. 2005; 88 (4):589–604. [ PubMed : 15796662 ]
• Beitchman JH, Baldassarra L, Mik H, Hons B, Vincenzo De Luca M, King N, Bender D, Ehtesham S, Kennedy JL. Serotonin transporter polymorphisms and persistent, pervasive childhood aggression. American Journal of Psychiatry. 2006; 163 (6):1103–1105. [ PubMed : 16741214 ]
• Belsky J, Pluess M. Beyond diathesis stress: Differential susceptibility to environmental influences. Psychological Bulletin. 2009; 135 (6):885–908. [ PubMed : 19883141 ]
• Belujon P, Grace AA. Regulation of dopamine system responsivity and its adaptive and pathological response to stress. Proceedings of the Royal Society of London B: Biological Sciences. 2015; 282 (1805):1–10. [ PMC free article : PMC4389605 ] [ PubMed : 25788601 ]
• Benjet C, Thompson RJ, Gotlib IH. 5-HTTLPR moderates the effect of relational peer victimization on depressive symptoms in adolescent girls. Journal of Child Psychology and Psychiatry. 2010; 51 (2):173–179. [ PMC free article : PMC2804775 ] [ PubMed : 19754661 ]
• Beran T. Correlates of peer victimization and achievement: An exploratory model. Psychology in the Schools. 2009; 46 (4):348–361.
• Beran TN, Lupart J. The relationship between school achievement and peer harassment in Canadian adolescents: The importance of mediating factors. School Psychology International. 2009; 30 (1):75–91.
• Beran TN, Hughes G, Lupart J. A model of achievement and bullying: Analyses of the Canadian National Longitudinal Survey of Children and Youth data. Educational Research. 2008; 50 (1):25–39.
• Blackburn EH, Epel ES. Nature. 7419. Vol. 490. 2012. pp. 169–171. [ PubMed : 23060172 ]
• Blakemore SJ. Development of the social brain in adolescence. Journal of the Royal Society of Medicine. 2012; 105 (3):111–116. [ PMC free article : PMC3308644 ] [ PubMed : 22434810 ]
• Boden JM, van Stockum S, Horwood LJ, Fergusson DM. Bullying victimization in adolescence and psychotic symptomatology in adulthood: Evidence from a 35-year study. Psychological Medicine. 2016; 46 (6):1311–1320. [ PubMed : 26804185 ]
• Bogart LM, Elliott MN, Klein DJ, Tortolero SR, Mrug S, Peskin MF, Davies SL, Schink ET, Schuster MA. Peer victimization in fifth grade and health in tenth grade. Pediatrics. 2014; 133 (3):440–447. [ PMC free article : PMC4530298 ] [ PubMed : 24534401 ]
• Boivin M, Brendgen M, Vitaro F, Dionne G, Girard A, Perusse D, Tremblay RE. Strong genetic contribution to peer relationship difficulties at school entry: Findings from a longitudinal twin study. Child Development. 2013; 84 (3):1098–1114. [ PubMed : 23210840 ]
• Booth A, Granger DA, Shirtcliff EA. Gender- and age-related differences in the association between social relationship quality and trait levels of salivary cortisol. Journal of Research on Adolescence. 2008; 18 (2):239–260.
• Borum R, Cornell DG, Modzeleski W, Jimerson SR. What can be done about school shootings? A review of the evidence. Educational Researcher. 2010; 39 (1):27–37.
• Bowes L, Joinson C, Wolke D, Lewis G. Peer victimisation during adolescence and its impact on depression in early adulthood: Prospective cohort study in the United Kingdom. The BMJ. 2015; 350 :1–9. [ PMC free article : PMC4452929 ] [ PubMed : 26037951 ]
• Boyce WT, Ellis BJ. Biological sensitivity to context: I. An evolutionary-developmental theory of the origins and functions of stress reactivity. Development and Psychopathology. 2005; 17 (2):271–301. [ PubMed : 16761546 ]
• Bradshaw CP, Sawyer AL, O'Brennan LM. A social disorganization perspective on bullying-related attitudes and behaviors: The influence of school context. American Journal of Community Psychology. 2009; 43 (3-4):204–220. [ PubMed : 19333749 ]
• Bradshaw CP, Goldweber A, Fishbein D, Greenberg MT. Infusing developmental neuroscience into school-based preventive interventions: Implications and future directions. Journal of Adolescent Health. 2012; 51 (2):S41–S47. [ PubMed : 22794533 ]
• Brendgen M. Genetics and peer relations: A review. Journal of Research on Adolescence. 2012; 22 (3):419–437.
• Bradshaw CP, Goldweber A, Garbarino J. Linking social-environmental risk factors with aggression in suburban adolescents: The role of social-cognitive mediators. Psychology in Schools. 2013; 50 (5):433–450.
• Brendgen M, Boivin M, Vitaro F, Bukowski WM, Dionne G, Tremblay RE, Pérusse D. Linkages between children's and their friends' social and physical aggression: Evidence for a gene–environment interaction? Child Development. 2008; 79 (1):13–29. [ PubMed : 18269506 ]
• Brendgen M, Girard A, Vitaro F, Dionne G, Boivin M. Do peer group norms moderate the expression of genetic risk for aggression? Journal of Criminal Justice. 2013; 41 (5):324–330.
• Buhs ES, Ladd GW, Herald SL. Peer exclusion and victimization: Processes that mediate the relation between peer group rejection and children's classroom engagement and achievement? Journal of Educational Psychology. 2006; 98 (1):1–13.
• Camodeca M, Goossens FA, Schuengel C, Terwogt MM. Links between social information processing in middle childhood and involvement in bullying. Aggressive Behavior. 2003; 29 (2):116–127.
• Casement MD, Guyer AE, Hipwell AE, McAloon RL, Hoffmann AM, Keenan KE, Forbes EE. Girls' challenging social experiences in early adolescence predict neural response to rewards and depressive symptoms. Developmental Cognitive Neuroscience. 2014; 8 :18–27. [ PMC free article : PMC3960334 ] [ PubMed : 24397999 ]
• Casey B, Jones RM. Neurobiology of the adolescent brain and behavior: Implications for substance use disorders. Journal of the American Academy of Child & Adolescent Psychiatry. 2010; 49 (12):1189–1201. [ PMC free article : PMC3099425 ] [ PubMed : 21093769 ]
• Caspi A, Sugden K, Moffitt TE, Taylor A, Craig IW, Harrington H, McClay J, Mill J, Martin J, Braithwaite A. Influence of life stress on depression: Moderation by a polymorphism in the 5-HTT gene. Science. 2003; 301 (5631):386–389. [ PubMed : 12869766 ]
• Chattarji S, Tomar A, Suvrathan A, Ghosh S, Rahman MM. Neighborhood matters: Divergent patterns of stress-induced plasticity across the brain. Nature Neuroscience. 2015; 18 (10):1364–1375. [ PubMed : 26404711 ]
• Cole DA, Peeke LG, Ingold C. Characterological and behavioral self-blame in children: Assessment and development considerations. Development and Psychopathology. 1996; 8 (02):381–397.
• Cook CR, Williams KR, Guerra NG, Kim TE, Sadek S. Predictors of bullying and victimization in childhood and adolescence: A meta-analytic investigation. School Psychology Quarterly. 2010; 25 (2):65–83.
• Copeland WE, Wolke D, Angold A, Costello EJ. Adult psychiatric outcomes of bullying and being bullied by peers in childhood and adolescence. Journal of the American Medical Association Psychiatry. 2013; 70 (4):419–426. [ PMC free article : PMC3618584 ] [ PubMed : 23426798 ]
• Copeland WE, Wolke D, Lereya ST, Shanahan L, Worthman C, Costello EJ. Childhood bullying involvement predicts low-grade systemic inflammation into adulthood. Proceedings of the National Academy of Sciences of the United States of America. 2014; 111 (21):7570–7575. [ PMC free article : PMC4040559 ] [ PubMed : 24821813 ]
• Cornell D. School Violence: Fears vs. Facts. New York: Routledge; 2006.
• Cosma A, Balazsi R, Dobrean A, Baban A. Bullying victimization, emotional problems and cognitive emotion regulation in adolescence. Psychology & Health. 2012; 27 :185–188.
• Cougnard A, Marcelis M, Myin-Germeys I, De Graaf R, Vollebergh W, Krabbendam L, Lieb R, Wittchen HU, Henquet C, Spauwen J. Does normal developmental expression of psychosis combine with environmental risk to cause persistence of psychosis? A psychosis proneness–persistence model. Psychological Medicine. 2007; 37 (04):513–527. [ PubMed : 17288646 ]
• Crick NR, Dodge KA. A review and reformulation of social information-processing mechanisms in children's social adjustment. Psychological Bulletin. 1994; 115 (1):74–101.
• Cunningham T, Hoy K, Shannon C. Does childhood bullying lead to the development of psychotic symptoms? A meta-analysis and review of prospective studies. Psychosis. 2015; 8 (1):1–12.
• Dahl RE, Gunnar MR. Heightened stress responsiveness and emotional reactivity during pubertal maturation: Implications for psychopathology. Development and Psychopathology. 2009; 21 (01):1–6. [ PubMed : 19144219 ]
• Dallman MF, Pecoraro N, Akana SF, La Fleur SE, Gomez F, Houshyar H, Bell M, Bhatnagar S, Laugero KD, Manalo S. Chronic stress and obesity: A new view of “comfort food.” Proceedings of the National Academy of Sciences of the United States of America. 2003; 100 (20):11696–11701. [ PMC free article : PMC208820 ] [ PubMed : 12975524 ]
• Danese A, Tan M. Childhood maltreatment and obesity: Systematic review and meta-analysis. Molecular Psychiatry. 2014; 19 (5):544–554. [ PubMed : 23689533 ]
• Danese A, Pariante CM, Caspi A, Taylor A, Poulton R. Childhood maltreatment predicts adult inflammation in a life-course study. Proceedings of the National Academy of Sciences of the United States of America. 2007; 104 (4):1319–1324. [ PMC free article : PMC1783123 ] [ PubMed : 17229839 ]
• de Bruyn E, Cillessen A, Wissink I. Associations of peer acceptance and perceived popularity with bullying and victimization in early adolescence. Journal of Early Adolescence. 2010; 30 (4):543–566.
• Dick DM, Agrawal A, Keller MC, Adkins A, Aliev F, Monroe S, Hewitt JK, Kendler KS, Sher KJ. Candidate gene–environment interaction research: Reflections and recommendations. Perspectives on Psychological Science. 2015; 10 (1):37–59. [ PMC free article : PMC4302784 ] [ PubMed : 25620996 ]
• Didden R, Scholte RHJ, Korzilius H, de Moor JMH, Vermeulen A, O'Reilly M, Lang R, Lancioni GE. Cyberbullying among students with intellectual and developmental disability in special education settings. Developmental Neurorehabilitation. 2009; 12 (3):146–151. [ PubMed : 19466622 ]
• Dijkstra JK, Lindenberg S, Veenstra R. Beyond the class norm: Bullying behavior of popular adolescents and its relation to peer acceptance and rejection. Journal of Abnormal Child Psychology. 2008; 36 (8):1289–1299. [ PubMed : 18607717 ]
• Dodge KA. Cognitive Perspectives on Children's Social and Behavioral Development: The Minnesota Symposia on Child Psychology, Volume 18. Perlmutter M, editor. New York: Psychology Press; 1986. pp. 77–125. (A social information processing model of social competence in children).
• Dodge KA, Bates JE, Pettit GS. Mechanisms in the cycle of violence. Science. 1990; 250 (4988):1678–1683. [ PubMed : 2270481 ]
• Duncan LE. Paying attention to all results, positive and negative. Journal of the American Academy of Child & Adolescent Psychiatry. 2013; 52 (5):462–465. [ PubMed : 23622847 ]
• Duncan LE, Keller MC. A critical review of the first 10 years of candidate gene-by-environment interaction research in psychiatry. Perspectives. 2011; 168 (10):1041–1049. [ PMC free article : PMC3222234 ] [ PubMed : 21890791 ]
• Duncan LE, Pollastri AR, Smoller JW. Mind the gap: Why many geneticists and psychological scientists have discrepant views about gene–environment interaction (G × E) research. American Psychologist. 2014; 69 (3):249–268. [ PMC free article : PMC7446184 ] [ PubMed : 24750075 ]
• Eisenberger NI. The neural bases of social pain: Evidence for shared representations with physical pain. Psychosomatic Medicine. 2012; 74 (2):126–135. [ PMC free article : PMC3273616 ] [ PubMed : 22286852 ]
• Eisenberger NI, Lieberman MD. Why rejection hurts: A common neural alarm system for physical and social pain. Trends in Cognitive Sciences. 2004; 8 (7):294–300. [ PubMed : 15242688 ]
• Eisenberger NI, Lieberman MD, Williams KD. Does rejection hurt? An fMRI study of social exclusion. Science. 2003; 302 (5643):290–292. [ PubMed : 14551436 ]
• Epel ES, Blackburn EH, Lin J, Dhabhar FS, Adler NE, Morrow JD, Cawthon RM. Accelerated telomere shortening in response to life stress. Proceedings of the National Academy of Sciences of the United States of America. 2004; 101 (49):17312–17315. [ PMC free article : PMC534658 ] [ PubMed : 15574496 ]
• Espelage DL, Swearer SM, editors. Bullying in American Schools: A Social-Ecological Perspective on Prevention and Intervention. Mahwah, NJ: Lawrence Erlbaum Associates; 2004.
• Espelage DL, Hong JS, Rao MA, Low S. Associations between peer victimization and academic performance. Theory Into Practice. 2013; 52 (4):233–240.
• Espinoza G, Gonzales NA, Fuligni AJ. Daily school peer victimization experiences among Mexican-American adolescents: Associations with psychosocial, physical, and school adjustment. Journal of Youth and Adolescence. 2013; 42 (12):1775–1788. [ PMC free article : PMC3951444 ] [ PubMed : 23238764 ]
• Euston DR, Gruber AJ, McNaughton BL. The role of medial prefrontal cortex in memory and decision making. Neuron. 2012; 76 (6):1057–1070. [ PMC free article : PMC3562704 ] [ PubMed : 23259943 ]
• Evans GW, Kim P, Ting AH, Tesher HB, Shannis D. Cumulative risk, maternal responsiveness, and allostatic load among young adolescents. Developmental Psychology. 2007; 43 (2):341. [ PubMed : 17352543 ]
• Faris R, Ennett S. Adolescent aggression: The role of peer group status motives, peer aggression, and group characteristics. Social Networks. 2012; 34 (4):371–378. [ PMC free article : PMC4138540 ] [ PubMed : 25152562 ]
• Farmer TW, Estell DB, Bishop JL, O'Neal KK, Cairns BD. Rejected bullies or popular leaders? The social relations of aggressive subtypes of rural African American early adolescents. Developmental Psychology. 2003; 39 (6):992–1004. [ PubMed : 14584980 ]
• Fein RA, Vossekuil B, Pollack WS, Borum R, Modzeleski W, Reddy M. Threat Assessment in Schools: A Guide to Managing Threatening Situations and Creating Safe School Climates. Washington, DC: U.S. Department of Education, Office of Elementary and Secondary Education, Safe and Drug-Free Schools Program and U.S. Secret Service, National Threat Assessment Center; 2002.
• Feldman MA, Ojanen T, Gesten EL, Smith-Schrandt H, Brannick M, Totura CMW, Alexander L, Scanga D, Brown K. The effects of middle school bullying and victimization on adjustment through high school: Growth modeling of achievement, school attendance, and disciplinary trajectories. Psychology in the Schools. 2014; 51 (10):1046–1062.
• Finkelhor D, Ormrod RK, Turner HA, Hamby SL. Measuring poly-victimization using the juvenile victimization questionnaire. Child Abuse & Neglect. 2005; 29 (11):1297–1312. [ PubMed : 16274741 ]
• Finkelhor D, Ormrod RK, Turner HA. Poly-victimization: A neglected component in child victimization. Child Abuse & Neglect. 2007; 31 (1):7–26. [ PubMed : 17224181 ]
• Finkelhor D, Ormrod RK, Turner HA. Lifetime assessment of poly-victimization in a national sample of children and youth. Child Abuse & Neglect. 2009; 33 (7):403–411. [ PubMed : 19589596 ]
• Flannery DJ, Modzeleski W, Kretschmar JM. Violence and school shootings. Current Psychiatry Reports. 2013; 15 (1):1–7. [ PubMed : 23254623 ]
• Flouri E, Buchanan A. The role of mother involvement and father involvement in adolescent bullying behavior. Journal of Interpersonal Violence. 2003; 18 (6):634–644.
• Ford JD, Elhai JD, Connor DF, Frueh BC. Poly-victimization and risk of posttraumatic, depressive, and substance use disorders and involvement in delinquency in a national sample of adolescents. Journal of Adolescent Health. 2010; 46 (6):545–552. [ PubMed : 20472211 ]
• Ford JD, Grasso DJ, Hawke J, Chapman JF. Poly-victimization among juvenile justice-involved youths. Child Abuse & Neglect. 2013; 37 (10):788–800. [ PubMed : 23428165 ]
• Forero R, McLellan L, Rissel C, Bauman A. Bullying behaviour and psychosocial health among school students in New South Wales, Australia, Cross-Sectional Survey. BMJ. 1999; 319 (7206):344–348. [ PMC free article : PMC28186 ] [ PubMed : 10435953 ]
• Ganzel BL, Kim P, Glover GH, Temple E. Resilience after 9/11: Multimodal neuroimaging evidence for stress-related change in the healthy adult brain. Neuroimage. 2008; 40 (2):788–795. [ PMC free article : PMC2405811 ] [ PubMed : 18234524 ]
• Gastic B. School truancy and the disciplinary problems of bullying victims. Educational Review. 2008; 60 (4):391–404.
• Gee DG, Gabard-Durnam L, Telzer EH, Humphreys KL, Goff B, Shapiro M, Flannery J, Lumian DS, Fareri DS, Caldera C. Maternal buffering of human amygdala-prefrontal circuitry during childhood but not during adolescence. Psychological Science. 2014 [ PMC free article : PMC4377225 ] [ PubMed : 25280904 ] [ CrossRef ]
• Gibb SJ, Horwood LJ, Fergusson DM. Bullying victimization/perpetration in childhood and later adjustment: Findings from a 30-year longitudinal study. Journal of Aggression, Conflict and Peace Research. 2011; 3 (2):82–88.
• Giedd JN, Blumenthal J, Jeffries NO, Castellanos FX, Liu H, Zijdenbos A, Paus T, Evans AC, Rapoport JL. Brain development during childhood and adolescence: A longitudinal MRI study. Nature Neuroscience. 1999; 2 (10):861–863. [ PubMed : 10491603 ]
• Gini G. Associations between bullying behaviour, psychosomatic complaints, emotional and behavioural problems. Journal of Paediatrics and Child Health. 2008; 44 (9):492–497. [ PubMed : 17608653 ]
• Gini G, Pozzoli T. Association between bullying and psychosomatic problems: A meta-analysis. Pediatrics. 2009; 123 (3):1059–1065. [ PubMed : 19255040 ]
• Gini G, Pozzoli T. Bullied children and psychosomatic problems: A meta-analysis. Pediatrics. 2013; 132 (4):720–729. [ PubMed : 24043275 ]
• Glew GM, Fan MY, Katon W, Rivara FP, Kernic MA. Bullying, psychosocial adjustment, and academic performance in elementary school. Archives of Pediatrics and Adolescent Medicine. 2005; 159 (11):1026–1031. [ PubMed : 16275791 ]
• Glew GM, Fan MY, Katon W, Rivara FP. Bullying and school safety. Journal of Pediatrics. 2008; 152 (1):123–128. [ PMC free article : PMC3839286 ] [ PubMed : 18154913 ]
• Graham S. Peer victimization in school: Exploring the ethnic context. Current Directions in Psychological Science. 2006; 15 (6):317–321.
• Graham S, Bellmore AD. Peer victimization and mental health during early adolescence. Theory into Practice. 2007; 46 (2):138–146.
• Graham S, Juvonen J. Self-blame and peer victimization in middle school: An attributional analysis. Developmental Psychology. 1998; 34 (3):587–599. [ PubMed : 9597367 ]
• Graham S, Bellmore AD, Mize J. Peer victimization, aggression, and their co-occurrence in middle school: Pathways to adjustment problems. Journal of Abnormal Child Psychology. 2006; 34 (3):349–364. [ PubMed : 16648999 ]
• Graham S, Bellmore A, Nishina A, Juvonen J. “It must be me”: Ethnic diversity and attributions for peer victimization in middle school. Journal of Youth and Adolescence. 2009; 38 (4):487–499. [ PubMed : 19636723 ]
• Greenberg DB. Somatization: Epidemiology, Pathogenesis, Clinical Features, Medical Evaluation, and Diagnosis. 2016. [June 2016]. http://www ​.uptodate.com ​/contents/somatizationtreatment-and-prognosis?source ​=see_link .
• Gross JJ. Emotion regulation in adulthood: Timing is everything. Current Directions in Psychological Science. 2001; 10 (6):214–219.
• Hager AD, Leadbeater BJ. The longitudinal effects of peer victimization on physical health from adolescence to young adulthood. Journal of Adolescent Health. 2016; 58 (3):330–336. [ PubMed : 26704181 ]
• Hanish LD, Eisenberg N, Fabes RA, Spinrad TL, Ryan P, Schmidt S. The expression and regulation of negative emotions: Risk factors for young children's peer victimization. Development and Psychopathology. 2004; 16 (02):335–353. [ PubMed : 15487599 ]
• Hanson JL, Nacewicz BM, Sutterer MJ, Cayo AA, Schaefer SM, Rudolph KD, Shirtcliff EA, Pollak SD, Davidson RJ. Behavioral problems after early life stress: Contributions of the hippocampus and amygdala. Biological Psychiatry. 2015; 77 (4):314–323. [ PMC free article : PMC4241384 ] [ PubMed : 24993057 ]
• Harris JR. Where is the child's environment? A group socialization theory of development. Psychological Review. 1995; 102 (3):458–489.
• Harvey AG, Tang NK. (Mis) perception of sleep in insomnia: A puzzle and a resolution. Psychological Bulletin. 2012; 138 (1):77–101. [ PMC free article : PMC3277880 ] [ PubMed : 21967449 ]
• Hawker DS, Boulton MJ. Twenty years' research on peer victimization and psychosocial maladjustment: A meta-analytic review of cross-sectional studies. Journal of Child Psychology and Psychiatry. 2000; 41 (4):441–455. [ PubMed : 10836674 ]
• Heim C, Owens MJ, Plotsky PM, Nemeroff CB. Persistent changes in corticotropin-releasing factor systems due to early life stress: Relationship to the pathophysiology of major depression and post-traumatic stress disorder. Psychopharmacology Bulletin. 1997; 33 (2):185–192. [ PubMed : 9230630 ]
• Hennessy MB, Kaiser S, Sachser N. Social buffering of the stress response: Diversity, mechanisms, and functions. Frontiers in Neuroendocrinology. 2009; 30 (4):470–482. [ PubMed : 19545584 ]
• Hennessy MB, Schiml PA, Willen R, Watanasriyakul W, Johnson J, Garrett T. Selective social buffering of behavioral and endocrine responses and Fos induction in the prelimbic cortex of infants exposed to a novel environment. Developmental Psychobiology. 2015; 57 (1):50–62. [ PubMed : 25355379 ]
• Herts KL, McLaughlin KA, Hatzenbuehler ML. Emotion dysregulation as a mechanism linking stress exposure to adolescent aggressive behavior. Journal of Abnormal Child Psychology. 2012; 40 (7):1111–1122. [ PMC free article : PMC3448707 ] [ PubMed : 22466516 ]
• Holt MK, Vivolo-Kantor AM, Polanin JR, Holland KM, DeGue S, Matjasko JL, Wolfe M, Reid G. Bullying and suicidal ideation and behaviors: A meta-analysis. Pediatrics. 2015; 135 (2):e496–e509. [ PMC free article : PMC4702491 ] [ PubMed : 25560447 ]
• Hostinar CE, Sullivan RM, Gunnar MR. Psychobiological mechanisms underlying the social buffering of the hypothalamic–pituitary–adrenocortical axis: A review of animal models and human studies across development. Psychological Bulletin. 2014; 140 (1):256–282. [ PMC free article : PMC3844011 ] [ PubMed : 23607429 ]
• Hostinar CE, Johnson AE, Gunnar MR. Parent support is less effective in buffering cortisol stress reactivity for adolescents compared to children. Developmental Science. 2015; 18 (2):281–297. [ PMC free article : PMC4270957 ] [ PubMed : 24942038 ]
• Huesmann LR, Guerra NG. Children's normative beliefs about aggression and aggressive behavior. Journal of Personality and Social Psychology. 1997; 72 (2):408–419. [ PubMed : 9107008 ]
• Hunter SC, Durkin K, Boyle JM, Booth JN, Rasmussen S. Adolescent bullying and sleep difficulties. Europe's Journal of Psychology. 2014; 10 (4):740–755.
• Institute of Medicine and National Research Council. Building Capacity to Reduce Bullying: Workshop Summary. Washington, DC: The National Academies Press; 2014a. [ PubMed : 25232636 ]
• Institute of Medicine and National Research Council. New Directions in Child Abuse and Neglect Research. Washington, DC: The National Academies Press; 2014b. [ PubMed : 24757747 ]
• Inzlicht M, McKay L, Aronson J. Stigma as ego depletion: How being the target of prejudice affects self-control. Psychological Science. 2006; 17 (3):262–269. [ PubMed : 16507068 ]
• Iyer PA, Dougall AL, Jensen-Campbell LA. Are some adolescents differentially susceptible to the influence of bullying on depression? Journal of Research in Personality. 2013; 47 (4):272–281.
• Janoff-Bulman R. Characterological versus behavioral self-blame: Inquiries into depression and rape. Journal of Personality and Social Psychology. 1979; 37 (10):1798–1809. [ PubMed : 512837 ]
• Jovanovic T, Smith A, Gamwell K, Nylocks M, Norrholm SD, Ressler KJ, Bradley B. Psychophysiological biomarkers of anxiety in children at high risk for trauma exposure. Biological Psychiatry. 2013; 73 (9):17S–17S.
• Judd LL, Schettler PJ, Brown ES, Wolkowitz OM, Sternberg EM, Bender BG, Bulloch K, Cidlowski JA, de Kloet ER, Fardet L. Adverse consequences of glucocorticoid medication: Psychological, cognitive, and behavioral effects. American Journal of Psychiatry. 2014; 171 (10):1045–1051. [ PubMed : 25272344 ]
• Juvonen J, Graham S. Bullying in schools: The power of bullies and the plight of victims. Annual Review of Psychology. 2014; 65 (1):159–185. [ PubMed : 23937767 ]
• Juvonen J, Nishina A, Graham S. Peer harassment, psychological adjustment, and school functioning in early adolescence. Journal of Educational Psychology. 2000; 92 (2):349–359.
• Juvonen J, Graham S, Schuster MA. Bullying among young adolescents: The strong, the weak, and the troubled. Pediatrics. 2003; 112 (6):1231–1237. [ PubMed : 14654590 ]
• Juvonen J, Wang Y, Espinoza G. Bullying experiences and compromised academic performance across middle school grades. Journal of Early Adolescence. 2011; 31 (1):152–173.
• Kalmakis KA, Chandler GE. Health consequences of adverse childhood experiences: A systematic review. Journal of the American Association of Nurse Practitioners. 2015; 27 (8):457–465. [ PubMed : 25755161 ]
• Karg K, Burmeister M, Shedden K, Sen S. The serotonin transporter promoter variant (5-HTTLPR), stress, and depression meta-analysis revisited: Evidence of genetic moderation. Archives of General Psychiatry. 2011; 68 (5):444–454. [ PMC free article : PMC3740203 ] [ PubMed : 21199959 ]
• Kidger J, Heron J, Leon DA, Tilling K, Lewis G, Gunnell D. Self-reported school experience as a predictor of self-harm during adolescence: A prospective cohort study in the south west of England (ALSPAC). Journal of Affective Disorders. 2015; 173 :163–169. [ PMC free article : PMC4286629 ] [ PubMed : 25462412 ]
• Kiecolt-Glaser JK, Gouin JP, Weng NP, Malarkey WB, Beversdorf DQ, Glaser R. Childhood adversity heightens the impact of later-life caregiving stress on telomere length and inflammation. Psychosomatic Medicine. 2011; 73 (1):16–22. [ PMC free article : PMC3051180 ] [ PubMed : 21148804 ]
• Kim YS, Leventhal B. Bullying and suicide. A review. International Journal of Adolescent Medicine and Health. 2008; 20 (2):133–154. [ PubMed : 18714552 ]
• Kim JH, Richardson R. New findings on extinction of conditioned fear early in development: Theoretical and clinical implications. Biological Psychiatry. 2010; 67 (4):297–303. [ PubMed : 19846065 ]
• Kim YS, Leventhal BL, Koh YJ, Hubbard A, Boyce WT. School bullying and youth violence: Causes or consequences of psychopathologic behavior? Archives of General Psychiatry. 2006; 63 (9):1035–1041. [ PubMed : 16953006 ]
• Kimmel MS, Mahler M. Adolescent masculinity, homophobia, and violence: Random school shootings, 1982-2001. American Behavioral Scientist. 2003; 46 (10):1439–1458.
• Klein J. The Bully Society: School Shootings and the Crisis of Bullying in America's Schools. New York: New York University Press; 2012.
• Kliewer W. Violence exposure and cortisol responses in urban youth. International Journal of Behavioral Medicine. 2006; 13 (2):109–120. [ PubMed : 16712428 ]
• Kliewer W, Dibble AE, Goodman KL, Sullivan TN. Physiological correlates of peer victimization and aggression in African American urban adolescents. Development and Psychopathology. 2012; 24 (2):637–650. [ PMC free article : PMC5828867 ] [ PubMed : 22559136 ]
• Klomek AB, Marrocco F, Kleinman M, Schonfeld IS, Gould MS. Bullying, depression, and suicidality in adolescents. Journal of the American Academy of Child & Adolescent Psychiatry. 2007; 46 (1):40–49. [ PubMed : 17195728 ]
• Klomek AB, Sourander A, Niemelä S, Kumpulainen K, Piha J, Tamminen T, Almqvist F, Gould MS. Childhood bullying behaviors as a risk for suicide attempts and completed suicides: A population-based birth cohort study. Journal of the American Academy of Child & Adolescent Psychiatry. 2009; 48 (3):254–261. [ PubMed : 19169159 ]
• Klomek AB, Sourander A, Gould M. The association of suicide and bullying in childhood to young adulthood: A review of cross-sectional and longitudinal research findings. Canadian Journal of Psychiatry. 2010; 55 (5):282–288. [ PubMed : 20482954 ]
• Klomek AB, Sourander A, Elonheimo H. Bullying by peers in childhood and effects on psychopathology, suicidality, and criminality in adulthood. The Lancet Psychiatry. 2015; 2 (10):930–941. [ PubMed : 26462227 ]
• Knack JM, Gomez HL, Jensen-Campbell LA. Social Pain: Neuropsychological and Health Implications of Loss and Exclusion. MacDonald G, Jensen-Campbell LA, editors. Washington, DC: American Psychological Association; 2011a. pp. 215–236. (Bullying and its long-term health implications).
• Knack JM, Jensen-Campbell LA, Baum A. Worse than sticks and stones? Bullying is associated with altered HPA axis functioning and poorer health. Brain and Cognition. 2011b; 77 (2):183–190. [ PubMed : 21839567 ]
• Knack J, Vaillancourt T, Hutcherson A. Psychology of Victimization. Hutcherson AN, editor. New York: Nova Science; 2012a. [June 2016]. pp. 205–218. (Evidence of altered cortisol levels across child maltreatment, intimate partner abuse, and peer victimization). https://www ​.novapublishers ​.com/catalog/product_info ​.php?products_id=27225 .
• Knack JM, Tsar V, Vaillancourt T, Hymel S, McDougall P. What protects rejected adolescents from also being bullied by their peers? The moderating role of peer-valued characteristics. Journal of Research on Adolescence. 2012b; 22 (3):467–479.
• Kochel KP, Ladd GW, Rudolph KD. Longitudinal associations among youth depressive symptoms, peer victimization, and low peer acceptance: An interpersonal process perspective. Child Development. 2012; 83 (2):637–650. [ PMC free article : PMC3305833 ] [ PubMed : 22313098 ]
• Kochenderfer BJ, Ladd GW. Peer victimization: Cause or consequence of school maladjustment? Child Development. 1996; 67 (4):1305–1317. [ PubMed : 8890485 ]
• Kowalski RM, Limber SP. Psychological, physical, and academic correlates of cyberbullying and traditional bullying. Journal of Adolescent Health. 2013; 53 (1):S13–S20. [ PubMed : 23790195 ]
• Kretschmer T, Dijkstra JK, Ormel J, Verhulst FC, Veenstra R. Dopamine receptor D4 gene moderates the effect of positive and negative peer experiences on later delinquency: The Tracking Adolescents' Individual Lives Survey study. Development and Psychopathology. 2013; 25 (4 pt. 1):1107–1117. [ PubMed : 24229552 ]
• Kross E, Berman MG, Mischel W, Smith EE, Wager TD. Social rejection shares somatosensory representations with physical pain. Proceedings of the National Academy of Sciences of the United States of America. 2011; 108 (15):6270–6275. [ PMC free article : PMC3076808 ] [ PubMed : 21444827 ]
• Kumpulainen K, Räsänen E, Puura K. Psychiatric disorders and the use of mental health services among children involved in bullying. Aggressive Behavior. 2001; 27 (2):102–110.
• Ladd GW, Kochenderfer-Ladd B. Identifying victims of peer aggression from early to middle childhood: Analysis of cross-informant data for concordance, estimation of relational adjustment, prevalence of victimization, and characteristics of identified victims. Psychological Assessment. 2002; 14 (1):74–96. [ PubMed : 11911051 ]
• Lake A, Chan M. Putting science into practice for early child development. The Lancet. 2015; 385 (9980):1816–1817. [ PubMed : 25245180 ]
• Langman P. Rampage school shooters: A typology. Aggression and Violent Behavior. 2009; 14 (1):79–86.
• Langman P. School Shooters: Understanding High School, College, and Adult Perpetrators. Lanham, MD: Rowman & Littlefield; 2015.
• Leary M, Kowalski R, Smith L, Phillips S. Teasing, rejection, and violence: Case studies of the school shootings. Aggressive Behavior. 2003; 29 (3):202–214.
• Lee HS, Lee JE, Lee KU, Kim YH. Neural changes associated with emotion processing in children experiencing peer rejection: A functional MRI study. Journal of Korean Medical Science. 2014; 29 (9):1293–1300. [ PMC free article : PMC4168185 ] [ PubMed : 25246750 ]
• Lereya ST, Copeland WE, Costello EJ, Wolke D. Adult mental health consequences of peer bullying and maltreatment in childhood: Two cohorts in two countries. The Lancet Psychiatry. 2015; 2 (6):524–531. [ PMC free article : PMC4580734 ] [ PubMed : 26360448 ]
• Lim L, Radua J, Rubia K. Gray matter abnormalities in childhood maltreatment: A voxel-wise meta-analysis. American Journal of Psychiatry. 2014; 171 (8):854–863. [ PubMed : 24781447 ]
• Lim L, Hart H, Mehta MA, Simmons A, Mirza K, Rubia K. Neural correlates of error processing in young people with a history of severe childhood abuse: An fMRI study. American Journal of Psychiatry. 2015; 172 (9):892–900. [ PubMed : 25882324 ]
• Liston C, McEwen B, Casey B. Psychosocial stress reversibly disrupts prefrontal processing and attentional control. Proceedings of the National Academy of Sciences of the United States of America. 2009; 106 (3):912–917. [ PMC free article : PMC2621252 ] [ PubMed : 19139412 ]
• Lodge J, Frydenberg E. The role of peer bystanders in school bullying: Positive steps toward promoting peaceful schools. Theory Into Practice. 2005; 44 (4):329–336.
• Lupien SJ, Fiocco A, Wan N, Maheu F, Lord C, Schramek T, Tu MT. Stress hormones and human memory function across the lifespan. Psychoneuroendocrinology. 2005; 30 (3):225–242. [ PubMed : 15511597 ]
• Madfis E. The Risk of School Rampage: Assessing and Preventing Threats of School Violence. New York: Polgrave MacMillan; 2014.
• Mahady Wilton MM, Craig WM, Pepler DJ. Emotional regulation and display in classroom victims of bullying: Characteristic expressions of affect, coping styles, and relevant contextual factors. Social Development. 2000; 9 (2):227–245.
• Márquez C, Poirier GL, Cordero MI, Larsen MH, Groner A, Marquis J, Magistretti PJ, Trono D, Sandi C. Peripuberty stress leads to abnormal aggression, altered amygdala and orbitofrontal reactivity and increased prefrontal MAOA gene expression. Translational Psychiatry. 2013; 3 (1):1–12. [ PMC free article : PMC3566724 ] [ PubMed : 23321813 ]
• McCormick CM, Mathews IZ. HPA function in adolescence: Role of sex hormones in its regulation and the enduring consequences of exposure to stressors. Pharmacology Biochemistry and Behavior. 2007; 86 (2):220–233. [ PubMed : 16901532 ]
• McDermott R, Tingley D, Cowden J, Frazzetto G, Johnson DD. Monoamine oxidase A gene (MAOA) predicts behavioral aggression following provocation. Proceedings of the National Academy of Sciences of the United States of America. 2009; 106 (7):2118–2123. [ PMC free article : PMC2650118 ] [ PubMed : 19168625 ]
• McDougall P, Vaillancourt T. Long-term adult outcomes of peer victimization in childhood and adolescence: Pathways to adjustment and maladjustment. American Psychologist. 2015; 70 (4):300–310. [ PubMed : 25961311 ]
• McEwen BS. Synaptic Stress and Pathogenesis of Neuropsychiatric Disorders. Popoli M, Diamond D, Sanacora G, editors. New York: Springer; 2014. pp. 1–18. (The brain on stress: The good and the bad).
• McEwen BS, Karatsoreos IN. Sleep deprivation and circadian disruption: Stress, allostasis, and allostatic load. Sleep Medicine Clinics. 2015; 10 (1):1–10. [ PMC free article : PMC8935364 ] [ PubMed : 26055668 ]
• McEwen BS, McEwen CA. Emerging Trends in the Social and Behavioral Sciences: An Interdisciplinary, Searchable, and Linkable Resource. Scott RA, Kosslyn SM, Pinkerton N, editors. New York: J. Wiley; 2015. pp. 1–15. (Social, psychological, and physiological reactions to stress).
• McEwen BS, Morrison JH. The brain on stress: Vulnerability and plasticity of the prefrontal cortext over the life course. Neuron. 2013; 79 (1):16–29. [ PMC free article : PMC3753223 ] [ PubMed : 23849196 ]
• McEwen BS, Gray JD, Nasca C. Recognizing resilience: Learning from the effects of stress on the brain. Neurobiology of Stress. 2015; 1 :1–11. [ PMC free article : PMC4260341 ] [ PubMed : 25506601 ]
• McGaugh JL. Consolidating memories. Annual Review of Psychology. 2015; 66 :1–24. [ PubMed : 25559113 ]
• McGee TR, Scott JG, McGrath JJ, Williams GM, O'Callaghan M, Bor W, Najman JM. Young adult problem behaviour outcomes of adolescent bullying. Journal of Aggression, Conflict and Peace Research. 2011; 3 (2):110–114.
• McGowan PO, Sasaki A, D'Alessio AC, Dymov S, Labonté B, Szyf M, Turecki G, Meaney MJ. Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse. Nature Neuroscience. 2009; 12 (3):342–348. [ PMC free article : PMC2944040 ] [ PubMed : 19234457 ]
• McGowan PO, Suderman M, Sasaki A, Huang T, Hallett M, Meaney MJ, Szyf M. Broad epigenetic signature of maternal care in the brain of adult rats. PLoS One. 2011; 6 (2) [August 2016]; http://journals ​.plos ​.org/plosone/article?id=10 ​.1371/journal.pone.0014739 . [ PMC free article : PMC3046141 ] [ PubMed : 21386994 ]
• McLaughlin KA, Hatzenbuehler ML, Hilt LM. Emotion dysregulation as a mechanism linking peer victimization to internalizing symptoms in adolescents. Journal of Consulting and Clinical Psychology. 2009; 77 (5):894–904. [ PMC free article : PMC2778003 ] [ PubMed : 19803569 ]
• Milaid MR, Quirk GJ. Fear extinction as a model for translational neuroscience: Ten years of progress. Annual Review of Psychology. 2012; 63 :129–151. [ PMC free article : PMC4942586 ] [ PubMed : 22129456 ]
• Miller GE, Chen E, Zhou ES. If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans. Psychological Bulletin. 2007; 133 (1):25–45. [ PubMed : 17201569 ]
• Miller GE, Chen E. Harsh family climate in early life presages the emergence of a proinflammatory phenotype in adolescence. Psychological Science. 2010; 21 (6):848–856. [ PMC free article : PMC3207635 ] [ PubMed : 20431047 ]
• Miller-Graff LE, Cater ÅK, Howell KH, Graham-Bermann SA. Victimization in childhood: General and specific associations with physical health problems in young adulthood. Journal of Psychosomatic Research. 2015; 70 (4):269–271. [ PubMed : 26208402 ]
• Moffitt TE. Teen-aged mothers in contemporary Britain. Journal of Child Psychology and Psychiatry. 2002; 43 (6):727–742. [ PubMed : 12236608 ]
• Montoya ER, Terburg D, Bos PA, Van Honk J. Testosterone, cortisol, and serotonin as key regulators of social aggression: A review and theoretical perspective. Motivation and Emotion. 2012; 36 (1):65–73. [ PMC free article : PMC3294220 ] [ PubMed : 22448079 ]
• Moriceau S, Sullivan RM. Maternal presence serves as a switch between learning fear and attraction in infancy. Nature Neuroscience. 2006; 9 (8):1004–1006. [ PMC free article : PMC1560090 ] [ PubMed : 16829957 ]
• Mulvey E, Cauffman E. The inherent limits of predicting school violence. American Psychologist. 2001; 56 (10):797–802. [ PubMed : 11675986 ]
• Musher-Eizenman DR, Boxer P, Danner S, Dubow EF, Goldstein SE, Heretick DML. Social-cognitive mediators of the relation of environmental and emotion regulation factors to children's aggression. Aggressive Behavior. 2004; 30 (5):389–408.
• Nair HP, Gonzalez-Lima F. Extinction of behavior in infant rats: Development of functional coupling between septal hippocampal and vental tegmental regions. The Journal of Neuroscience. 1999; 19 (19):8646–8655. [ PMC free article : PMC6783035 ] [ PubMed : 10493765 ]
• Nakamoto J, Schwartz D. Is peer victimization associated with academic achievement? A meta-analytic review. Social Development. 2010; 19 (2):221–242.
• Nansel TR, Overpeck M, Pilla RS, Ruan WJ, Simons-Morton B, Scheidt P. Bullying behaviors among U.S. youth: Prevalence and association with psychosocial adjustment. Journal of the American Medical Association. 2001; 285 (16):2094–2100. [ PMC free article : PMC2435211 ] [ PubMed : 11311098 ]
• Nansel TR, Haynie DL, Simonsmorton BG. The association of bullying and victimization with middle school adjustment. Journal of Applied School Psychology. 2003; 19 (2):45–61.
• Nansel TR, Craig W, Overpeck MD, Saluja G, Ruan WJ. Cross-national consistency in the relationship between bullying behaviors and psychosocial adjustment. Archives of Pediatrics and Adolescent Medicine. 2004; 158 (8):730–736. [ PMC free article : PMC2556236 ] [ PubMed : 15289243 ]
• National Research Council and Institute of Medicine; Division of Behavioral and Social Sciences and Education. Deadly Lessons: Understanding Lethal School Violence. Moore MH, Petrie CV, Braga AA, McLaughlin BL, editors. Washington, DC: The National Academies Press; 2003. (Case Studies of School Violence Committee).
• Neary A, Joseph S. Peer victimization and its relationship to self-concept and depression among schoolgirls. Personality and Individual Differences. 1994; 16 (1):183–186.
• Newman KS, Fox C, Harding D, Mehta J, Roth W. Rampage: The Social Roots of School Shootings. New York: Basic Books; 2004.
• Newman ML. Here we go again: Bullying history and cardiovascular responses to social exclusion. Physiology & Behavior. 2014; 133 :76–80. [ PubMed : 24858188 ]
• Nishina A, Juvonen J. Daily reports of witnessing and experiencing peer harassment in middle school. Child Development. 2005; 76 (2):435–450. [ PubMed : 15784092 ]
• Niv S, Tuvblad C, Raine A, Baker LA. Aggression and rule-breaking: Heritability and stability of antisocial behavior problems in childhood and adolescence. Journal of Criminal Justice. 2013; 41 (5):285–291. [ PMC free article : PMC3856338 ] [ PubMed : 24347737 ]
• Nixon C. Current perspectives: The impact of cyberbullying on adolescent health. Adolescent Health, Medicine and Therapeutics. 2014:143–158. [ PMC free article : PMC4126576 ] [ PubMed : 25177157 ]
• O'Brennan LM, Bradshaw CP, Sawyer AL. Examining developmental differences in the social-emotional problems among frequent bullies, victims, and bully/victims. Psychology in the Schools. 2009; 46 (2):100–115.
• Obradovic J, Bush NR, Stamperdahl J, Adler NE, Boyce WT. Biological sensitivity to context: The interactive effects of stress reactivity and family adversity on socioemotional behavior and school readiness. Child Development. 2010; 81 (1):270–289. [ PMC free article : PMC2846098 ] [ PubMed : 20331667 ]
• Olweus D. Bullying at School. What We Know and What We Can Do. Oxford, UK: Blackwell; 1993a.
• Olweus D. Social Withdrawal, Inhibition, and Shyness in Childhood. Rubin KH, Asendorpf JB, editors. New York: Psychology Press; 1993b. pp. 315–341. (Victimization by peers: Antecedents and long-term outcomes).
• Ostrov JM, Kamper KE. Future directions for research on the development of relational and physical peer victimization. Journal of Clinical Child & Adolescent Psychology. 2015; 44 (3):509–519. [ PubMed : 25751392 ]
• O'Toole ME. The School Shooter: A Threat Assessment Perspective. Quantico, VA: US Department of Justice, Federal Bureau of Investigation; 2000.
• O'Toole ME, Folino PJ, Garbarino J, Gorelick SM, Häkkänen-Nyholm H, Meloy JR, Samenow SE, Nishimura YS. Why do young males attack schools? Seven discipline leaders share their perspectives. Violence and Gender. 2014; 1 (1):13–18.
• Ouellet-Morin I, Odgers CL, Danese A, Bowes L, Shakoor S, Papadopoulos AS, Caspi A, Moffitt TE, Arseneault L. Blunted cortisol responses to stress signal social and behavioral problems among maltreated/bullied 12-year-old children. Biological Psychiatry. 2011; 70 (11):1016–1023. [ PMC free article : PMC3816750 ] [ PubMed : 21839988 ]
• Ouellet-Morin I, Wong C, Danese A, Pariante C, Papadopoulos A, Mill J, Arseneault L. Increased serotonin transporter gene (SERT) DNA methylation is associated with bullying victimization and blunted cortisol response to stress in childhood: A longitudinal study of discordant monozygotic twins. Psychological Medicine. 2013; 43 (09):1813–1823. [ PMC free article : PMC4231789 ] [ PubMed : 23217646 ]
• Patchin JW. Bullies move beyond the schoolyard: A preliminary look at cyberbullying. Youth Violence and Juvenile Justice. 2006; 4 (2):148–169.
• Patton DU, Hong JS, Patel S, Kral MJ. A systematic review of research strategies used in qualitative studies on school bullying and victimization. Trauma, Violence, & Abuse. 2015:1–14. [ PubMed : 26092753 ] [ CrossRef ]
• Pattwell SS, Duhoux S, Hartley CA, Johnson DC, Jing D, Elliott MD, Ruberry EJ, Powers A, Mehta N, Yand RR, Soliman F, Glatt CE, Casey BJ, Ninan I, Lee FS. Altered fear learning across development in both mouse and human. Proceedings of the National Academy of Sciences of the United States of America. 2012; 109 (40):16318–16323. [ PMC free article : PMC3479553 ] [ PubMed : 22988092 ]
• Pattwell SS, Lee FS, Casey BJ. Fear learning and memory across adolescent development: Hormones and behavior special issue: Puberty and adolescence. Hormones and Behavior. 2013; 64 (2):380–389. [ PMC free article : PMC3761221 ] [ PubMed : 23998679 ]
• Peeters M, Cillessen AH, Scholte RH. Clueless or powerful? Identifying subtypes of bullies in adolescence. Journal of Youth and Adolescence. 2010; 39 (9):1041–1052. [ PubMed : 20625880 ]
• Perren S, Ettekal I, Ladd G. The impact of peer victimization on later maladjustment: Mediating and moderating effects of hostile and self-blaming attributions. Journal of Child Psychology and Psychiatry. 2012; 54 (1):46–55. [ PMC free article : PMC3527635 ] [ PubMed : 23057732 ]
• Perry R, Sullivan RM. Neurobiology of attachment to an abusive caregiver: Short-term benefits and long-term costs. Developmental Psychobiology. 2014; 56 (8):1626–1634. [ PMC free article : PMC4209208 ] [ PubMed : 24771610 ]
• Plomin R, DeFries JC, Loehlin JC. Genotype-environment interaction and correlation in the analysis of human behavior. Psychological Bulletin. 1977; 84 (2):309–322. [ PubMed : 557211 ]
• Polanin JR, Espelage DL, Pigott TD. A meta-analysis of school-based bullying prevention programs' effects on bystander intervention behavior. School Psychology Review. 2012; 41 (1):47–65.
• Prinstein MJ, Cheah CSL, Guyer AE. Peer victimization, cue interpretation, and internalizing symptoms: Preliminary concurrent and longitudinal findings for children and adolescents. Journal of Clinical Child & Adolescent Psychology. 2005; 34 (1):11–24. [ PubMed : 15677277 ]
• Radley JJ, Rocher AB, Miller M, Janssen WG, Liston C, Hof PR, McEwen BS, Morrison JH. Repeated stress induces dendritic spine loss in the rat medial prefrontal cortex. Cerebral Cortex. 2006; 16 (3):313–320. [ PubMed : 15901656 ]
• Radliff KM, Wheaton JE, Robinson K, Morris J. Illuminating the relationship between bullying and substance use among middle and high school youth. Addictive Behaviors. 2012; 37 (4):569–572. [ PubMed : 22277772 ]
• Rau V, Fanselow MS. Exposure to a stressor produces a long lasting enhancement of fear learning in rats: Original research report. Stress. 2009; 12 (2):125–133. [ PubMed : 18609302 ]
• Reijntjes A, Kamphuis JH, Prinzie P, Telch MJ. Peer victimization and internalizing problems in children: A meta-analysis of longitudinal studies. Child Abuse & Neglect. 2010; 34 (4):244–252. [ PubMed : 20304490 ]
• Reijntjes A, Kamphuis JH, Prinzie P, Boelen PA, Van der Schoot M, Telch MJ. Prospective linkages between peer victimization and externalizing problems in children: A meta-analysis. Aggressive Behavior. 2011; 37 (3):215–222. [ PubMed : 21433031 ]
• Repetti RL, Taylor SE, Seeman TE. Risky families: Family social environments and the mental and physical health of offspring. Psychological Bulletin. 2002; 128 (2):330–366. [ PubMed : 11931522 ]
• Retz W, Retz-Junginger P, Supprian T, Thome J, Rösler M. Association of serotonin transporter promoter gene polymorphism with violence: Relation with personality disorders, impulsivity, and childhood adhd psychopathology. Behavioral Sciences & the Law. 2004; 22 (3):415–425. [ PubMed : 15211560 ]
• Reuter-Rice K. Male adolescent bullying and the school shooter. Journal of School Nursing. 2008; 24 (6):350–359. [ PubMed : 19114465 ]
• Richter-Levin G, Horovitz O, Tsoory MM. Future Directions in Post-Traumatic Stress Disorder: Prevention Diagnosis, and Treatment. Safir MP, Wallach HS, Rizzo A, editors. New York: Springer; 2015. (The early adolescent of “juvenile stress” translational animal model of posttraumatic stress disorder).
• Rigby K, Slee PT. Dimensions of interpersonal relation among Australian children and implications for psychological well-being. Journal of Social Psychology. 1993; 133 (1):33–42. [ PubMed : 8464217 ]
• Rivers I, Noret N. Potential suicide ideation and its association with observing bullying at school. Journal of Adolescent Health. 2013; 53 (1):S32–S36. [ PubMed : 23790198 ]
• Rivers I, Poteat VP, Noret N, Ashurst N. Observing bullying at school: The mental health implications of witness status. School Psychology Quarterly. 2009; 24 (4):211–223.
• Robertson KD. DNA methylation and human disease. Nature Reviews: Genetics. 2005; 6 (8):597–610. [ PubMed : 16136652 ]
• Rocque M. Exploring school rampage shootings: Research, theory, and policy. Social Science Journal. 2012; 49 (3):304–313.
• Rodkin PC. Bullying in American Schools: A Social-Ecological Perspective on Prevention and Intervention. Espelage DL, Swearer SM, editors. Mahwah, NJ: Lawrence Erlbaum Associates; 2004. pp. 87–106. (Peer ecologies of aggression and bullying).
• Rodkin PC, Espelage DL, Hanish LD. A relational framework for understanding bullying: Developmental antecedents and outcomes. American Psychologist. 2015; 70 (4):311–321. [ PubMed : 25961312 ]
• Romeo RD. Pubertal maturation and programming of hypothalamic–pituitary–adrenal reactivity. Frontiers in Neuroendocrinology. 2010; 31 (2):232–240. [ PubMed : 20193707 ]
• Romeo RD. Perspectives on stress resilience and adolescent neurobehavioral function. Neurobiology of Stress. 2015; 1 :128–133. [ PMC free article : PMC4721430 ] [ PubMed : 27589663 ]
• Roth TL. How traumatic experiences leave their signature on the genome: An overview of epigenetic pathways in PTSD. Frontiers in Psychiatry. 2014; 5 (93):1–2. [ PMC free article : PMC4116797 ] [ PubMed : 25132824 ]
• Roth TL, Sweatt JD. Epigenetic marking of the BDNF gene by early-life adverse experiences. Hormones and Behavior. 2011; 59 (3):315–320. [ PMC free article : PMC2948595 ] [ PubMed : 20483357 ]
• Rudolph KD, Troop-Gordon W, Flynn M. Relational victimization predicts children's social-cognitive and self-regulatory responses in a challenging peer context. Developmental Psychology. 2009; 45 (5):1444–1454. [ PMC free article : PMC2780469 ] [ PubMed : 19702404 ]
• Rudolph KD, Miernicki ME, Troop-Gordon W, Davis MM, Telzer EH. Adding insult to injury: Neural sensitivity to social exclusion is associated with internalizing symptoms in chronically peer-victimized girls. Social Cognitive and Affective Neuroscience. 2016 [ PMC free article : PMC4847705 ] [ PubMed : 26892162 ] [ CrossRef ]
• Rueger SY, Jenkins LN. Effects of peer victimization on psychological and academic adjustment in early adolescence. School Psychology Quarterly. 2014; 29 (1):77–88. [ PubMed : 24015982 ]
• Rueger SY, Malecki CK, Demaray MK. Stability of peer victimization in early adolescence: Effects of timing and duration. Journal of School Psychology. 2011; 49 (4):443–464. [ PubMed : 21724000 ]
• Salmivalli C. Bullying and the peer group: A review. Aggression and Violent Behavior. 2010; 15 (2):112–120.
• Salmivalli C, Lagerspetz K, Björkqvist K, Österman K, Kaukiainen A. Bullying as a group process: Participant roles and their relations to social status within the group. Aggressive Behavior. 1996; 22 (1):1–15.
• Salmivalli C, Voeten M, Poskiparta E. Bystanders matter: Associations between reinforcing, defending, and the frequency of bullying behavior in classrooms. Journal of Clinical Child & Adolescent Psychology. 2011; 40 (5):668–676. [ PubMed : 21916686 ]
• Sanchez M, Pollak S. Handbook of Developmental Social Neuroscience. de Haan M, Gunnar MR, editors. New York: Guilford Press; 2009. pp. 497–520. (Socio-emotional development following early abuse and neglect: Challenges and insights from translational research).
• Sandi C, Haller J. Stress and the social brain: Behavioural effects and neurobiological mechanisms. Nature Reviews Neuroscience. 2015; 16 :290–304. [ PubMed : 25891510 ]
• Scarr S, McCartney K. How people make their own environments: A theory of genotype→ environment effects. Child Development. 1983; 52 (2):424–435. [ PubMed : 6683622 ]
• Schacter HL, White SJ, Chang VY, Juvonen J. “Why me?”: Characterological self-blame and continued victimization in the first year of middle school. Journal of Clinical Child & Adolescent Psychology. 2014; 44 (3):446–455. [ PMC free article : PMC6129379 ] [ PubMed : 24483145 ]
• Schwartz D, Dodge KA, Coie JD. The emergence of chronic peer victimization in boys' play groups. Child Development. 1993; 64 (6):1755–1772. [ PubMed : 8112117 ]
• Schwartz D, Gorman AH, Nakamoto J, Toblin RL. Victimization in the peer group and children's academic functioning. Journal of Educational Psychology. 2005; 97 (3):425–435.
• Shakoor S, Jaffee SR, Andreou P, Bowes L, Ambler AP, Caspi A, Moffitt TE, Arseneault L. Mothers and children as informants of bullying victimization: Results from an epidemiological cohort of children. Journal of Abnormal Child Psychology. 2011; 39 (3):379–387. [ PMC free article : PMC4231790 ] [ PubMed : 20938734 ]
• Shalev I, Moffitt TE, Sugden K, Williams B, Houts RM, Danese A, Mill J, Arseneault L, Caspi A. Exposure to violence during childhood is associated with telomere erosion from 5 to 10 years of age: A longitudinal study. Molecular Psychiatry. 2013; 18 (5):576–581. [ PMC free article : PMC3616159 ] [ PubMed : 22525489 ]
• Shen J, Kudrimoti H, McNaughton B, Barnes C. Reactivation of neuronal ensembles in hippocampal dentate gyrus during sleep after spatial experience. Journal of Sleep Research. 1998; 7 (S1):6–16. [ PubMed : 9682188 ]
• Shonkoff JP, Boyce WT, McEwen BS. Neuroscience, molecular biology, and the childhood roots of health disparities: Building a new framework for health promotion and disease prevention. Journal of the American Medical Association. 2009; 301 (21):2252–2259. [ PubMed : 19491187 ]
• Shultz JM, Thoresen S, Flynn BW, Muschert GW, Shaw JA, Espinel Z, Walter FG, Gaither JB, Garcia-Barcena Y, O'Keefe K. Multiple vantage points on the mental health effects of mass shootings. Current Psychiatry Reports. 2014; 16 (9):1–17. [ PubMed : 25085235 ]
• Sigurdson JF, Undheim AM, Wallander JL, Lydersen S, Sund AM. The long-term effects of being bullied or a bully in adolescence on externalizing and internalizing mental health problems in adulthood. Child and Adolescent Psychiatry and Mental Health. 2015; 9 (1):1–13. [ PMC free article : PMC4546259 ] [ PubMed : 26300969 ]
• Sijtsema JJ, Veenstra R, Lindenberg S, Salmivalli C. Empirical test of bullies' status goals: Assessing direct goals, aggression, and prestige. Aggressive Behavior. 2009; 35 :57–67. [ PubMed : 18925635 ]
• Smalley D, Banerjee R. The role of social goals in bullies' and victims' social information processing in response to ambiguous and overtly hostile provocation. Social Development. 2013; 23 (3):593–610.
• Smith PK, Talamelli L, Cowie H, Naylor P, Chauhan P. Profiles of non-victims, escaped victims, continuing victims and new victims of school bullying. British Journal of Educational Psychology. 2004; 74 :565–581. [ PubMed : 15530202 ]
• Sourander A, Jensen P, Rönning JA, Elonheimo H, Niemelä S, Helenius H, Kumpulainen K, Piha J, Tamminen T, Moilanen I, Almqvist F. Childhood bullies and victims and their risk of criminality in late adolescence. Archives of Pediatrics and Adolescent Medicine. 2007; 161 (6):546–552. [ PubMed : 17548758 ]
• Sourander A, Brunstein KA, Kumpulainen K, Puustjärvi A, Elonheimo H, Ristkari T, Tamminen T, Moilanen I, Piha J, Ronning J. Bullying at age eight and criminality in adulthood: Findings from the Finnish Nationwide 1981 Birth Cohort Study. Social Psychiatry and Psychiatric Epidemiology. 2011; 46 (12):1211–1219. [ PubMed : 21120451 ]
• Spear L. The Behavioral Neuroscience of Adolescence. New York: WW Norton & Company; 2010.
• Spear LP. Adolescent neurodevelopment. Journal of Adolescent Health. 2013; 52 (2):S7–S13. [ PMC free article : PMC3982854 ] [ PubMed : 23332574 ]
• Srabstein JC, McCarter RJ, Shao C, Huang ZJ. Morbidities associated with bullying behaviors in adolescents. School based study of American adolescents. International Journal of Adolescent Medicine and Health. 2006; 18 (4):587–596. [ PubMed : 17340850 ]
• Stapinski LA, Bowes L, Wolke D, Pearson RM, Mahedy L, Button KS, Lewis G, Araya R. Peer victimization during adolescence and risk for anxiety disorders in adulthood: A prospective cohort study. Depression and anxiety. 2014; 31 (7):574–582. [ PMC free article : PMC4190687 ] [ PubMed : 24788688 ]
• Sugden K, Arseneault L, Harrington H, Moffitt TE, Williams B, Caspi A. Serotonin transporter gene moderates the development of emotional problems among children following bullying victimization. Journal of the American Academy of Child & Adolescent Psychiatry. 2010; 49 (8):830–840. [ PMC free article : PMC2908591 ] [ PubMed : 20643316 ]
• Swearer SM, Hymel S. Understanding the psychology of bullying: Moving toward a social-ecological diathesis–stress model. American Psychologist. 2015; 70 (4):344–353. [ PubMed : 25961315 ]
• Tharp-Taylor S, Haviland A, D'Amico EJ. Victimization from mental and physical bullying and substance use in early adolescence. Addictive Behaviors. 2009; 34 (6):561–567. [ PMC free article : PMC2707251 ] [ PubMed : 19398162 ]
• Thornberg R, Tenenbaum L, Varjas K, Meyers J, Jungert T, Vanegas G. Bystander motivation in bullying incidents: To intervene or not to intervene? Western Journal of Emergency Medicine. 2012; 13 (3):247–252. [ PMC free article : PMC3415829 ] [ PubMed : 22900122 ]
• Thunfors P, Cornell D. The popularity of middle school bullies. Journal of School Violence. 2008; 7 (1):65–82.
• Tilghman-Osborne C, Cole DA, Felton JW, Ciesla JA. Relation of guilt, shame, behavioral and characterological self-blame to depressive symptoms in adolescents over time. Journal of Social and Clinical Psychology. 2008; 27 (8):809–842. [ PMC free article : PMC4238306 ] [ PubMed : 25419043 ]
• Ttofi MM, Farrington DP, Lösel F, Loeber R. Do the victims of school bullies tend to become depressed later in life? A systematic review and meta-analysis of longitudinal studies. Journal of Aggression, Conflict and Peace Research. 2011; 3 (2):63–73.
• Unnever JD, Cornell DG. The culture of bullying in middle school. Journal of School Violence. 2003; 2 (2):5–27.
• Vaillancourt T, Hymel S, McDougall P. Bullying is power: Implications for school-based intervention strategies. Journal of Applied School Psychology. 2003; 19 (2):157–176.
• Vaillancourt T, Duku E, Decatanzaro D, Macmillan H, Muir C, Schmidt LA. Variation in hypothalamic–pituitary–adrenal axis activity among bullied and non-bullied children. Aggressive Behavior. 2008; 34 (3):294–305. [ PubMed : 18161876 ]
• Vaillancourt T, Decatanzaro D, Duku E, Muir C. Androgen dynamics in the context of children's peer relations: An examination of the links between testosterone and peer victimization. Aggressive Behavior. 2009; 35 (1):103–113. [ PubMed : 19021234 ]
• Vaillancourt T, Hymel S, McDougall P. Bullying in North American Schools. Espelage D, Swearer S, editors. New York: Taylor & Francis; 2010a. pp. 23–33. (Why does bullying hurt so much? Insights from neuroscience).
• Vaillancourt T, McDougall P, Hymel S, Sunderani S. Handbook of Bullying in Schools: An International Perspective. Jimerson SR, Swearer SM, Espelage DL, editors. New York: Routledge; 2010b. pp. 211–222. (The relationship between power and bullying behavior).
• Vaillancourt T, Duku E, Becker S, Schmidt LA, Nicol J, Muir C, MacMillan H. Peer victimization, depressive symptoms, and high salivary cortisol predict poorer memory in children. Brain and Cognition. 2011; 77 (2):191–199. [ PubMed : 21855200 ]
• Vaillancourt T, Hymel S, McDougall P. The biological underpinnings of peer victimization: Understanding why and how the effects of bullying can last a lifetime. Theory Into Practice. 2013a; 52 (4):241–248.
• Vaillancourt T, Brittain HL, McDougall P, Duku E. Longitudinal links between childhood peer victimization, internalizing and externalizing problems, and academic functioning: Developmental cascades. Journal of Abnormal Child Psychology. 2013b; 41 (8):1203–1215. [ PubMed : 23907699 ]
• Vaillancourt T, Sanderson C, Arnold P, McDougall P. Handbook of Bullying Prevention: A Life Course Perspective. Bradshaw CP, editor. National Association of Social Workers Press; (The neurobiology of peer victimization: Longitudinal links to health, genetic risk, and epigenetic mechanisms). in press.
• van Dam DS, van der Ven E, Velthorst E, Selten JP, Morgan C, de Haan L. Childhood bullying and the association with psychosis in non-clinical and clinical samples: A review and meta-analysis. Psychological Medicine. 2012; 42 (12):2463–2474. [ PubMed : 22400714 ]
• van Geel M, Vedder P, Tanilon J. Relationship between peer victimization, cyberbullying, and suicide in children and adolescents. Journal of American Medical Association Pediatrics. 2014; 168 (5):435–442. [ PubMed : 24615300 ]
• van Geel M, Goemans A, Vedder PH. The relation between peer victimization and sleeping problems: A meta-analysis. Sleep Medicine Reviews. 2015; 27 :89–95. [ PubMed : 26140869 ]
• Vannucci M, Nocentini A, Mazzoni G, Menesini E. Recalling unpresented hostile words: False memories predictors of traditional and cyberbullying. European Journal of Developmental Psychology. 2012; 9 (2):182–194.
• VanZomeren-Dohm AA, Pitula CE, Koss KJ, Thomas K, Gunnar MR. FKBP5 moderation of depressive symptoms in peer victimized, post-institutionalized children. Psychoneuroendocrinology. 2015; 51 :426–430. [ PMC free article : PMC4268402 ] [ PubMed : 25462914 ]
• Veenstra R, Lindenberg S, Munniksma A, Dijkstra JK. The complex relation between bullying, victimization, acceptance, and rejection: Giving special attention to status, affection, and sex differences. Child Development. 2010; 81 (2):480–486. [ PubMed : 20438454 ]
• Viding E, Blair RJR, Moffitt TE, Plomin R. Evidence for substantial genetic risk for psychopathy in 7-year-olds. Journal of Child Psychology and Psychiatry. 2005; 46 (6):592–597. [ PubMed : 15877765 ]
• Vossekuil B, Fein RA, Reddy M, Borum R, Modzeleski W. The Final Report and Findings of the Safe School Initiative: Implications for the Prevention of the Safe School Initiative. Washington, DC: U.S. Secret Service and Department of Education; 2002.
• Weaver IC, Cervoni N, Champagne FA, D'Alessio AC, Sharma S, Seckl JR, Dymov S, Szyf M, Meaney MJ. Epigenetic programming by maternal behavior. Nature Neuroscience. 2004; 7 (8):847–854. [ PubMed : 15220929 ]
• Weiner B. An Attributional Theory of Motivation and Emotion. New York: Springer-Verlag; 1986.
• Whelan YM, Kretschmer T, Barker ED. MAOA, early experiences of harsh parenting, irritable opposition, and bullying–victimization: A moderated indirect-effects analysis. Merrill-Palmer Quarterly. 2014; 60 (2):217–237.
• Wilker S, Pfeiffer A, Kolassa S, Elbert T, Lingenfelder B, Ovuga E, Papassotiropoulos A, de Quervain D, Kolassa IT. The role of FKBP5 genotype in moderating long-term effectiveness of exposure-based psychotherapy for posttraumatic stress disorder. Translational Psychiatry. 2014; 4 (6):1–7. [ PMC free article : PMC4080328 ] [ PubMed : 24959896 ]
• Williams KD, Bernieri FJ, Faulkner SL, Gada-Jain N, Grahe JE. The Scarlet Letter Study: Five days of social ostracism. Journal of Personal & Interpersonal Loss. 2000; 5 (1):19–63.
• Wilson TD, Damiani M, Shelton N. Improving Academic Achievement: Impact of Psychological Factors on Education. Wilson TD, editor. San Diego, CA: Elsevier BV; 2002. pp. 89–108. (Improving the academic performance of college students with brief attributional interventions).
• Wolke D, Woods S, Bloomfield L, Karstadt L. Bullying involvement in primary school and common health problems. Archives of Disease in Childhood. 2001; 85 (3):197–201. [ PMC free article : PMC1718894 ] [ PubMed : 11517098 ]
• Wolke D, Lereya ST, Fisher H, Lewis G, Zammit S. Bullying in elementary school and psychotic experiences at 18 years: A longitudinal, population-based cohort study. Psychological Medicine. 2014; 44 (10):2199–2211. [ PubMed : 24342773 ]
• Yang GS, McLoyd VC. Do parenting and family characteristics moderate the relation between peer victimization and antisocial behavior? A 5-year longitudinal study. Social Development. 2015; 24 :748–765.
• Ybarra ML, Mitchell KJ, Wolak J, Finkelhor D. Examining characteristics and associated distress related to Internet harassment: Findings from the second Youth Internet Safety Survey. Pediatrics. 2006; 118 (4):e1169–e1177. [ PubMed : 17015505 ]

Somatization is “a syndrome of physical symptoms that are distressing and may not be fully explained by a known medical condition after appropriate investigation. In addition, the symptoms may be caused or exacerbated by anxiety, depression, and interpersonal conflicts, and it is common for somatization, depression, and anxiety to all occur together” ( Greenberg, 2016 ).

Consolidation of memory is a biological process where the information one learns is stabilized within neural circuits and placed into long-term memory through a complex orchestration of molecular-level change and gene activation within neurons.

Peer victimization was measured with a 21-item revised version of the Social Experiences Questionnaire. The measure assesses overt and relational victimization and frequency of different acts of victimization ( Rudolph et al., 2016 ).

Reijntjes and colleagues (2010, p. 244) defined peer victimization as taking “various forms, including direct bullying behaviors (e.g., teasing, physical aggression) as well as more indirect manifestations such as group exclusion or malicious gossip.” Hawker and Boulton (2000, p. 441) defined peer victimization as “the experience among children of being a target of the aggressive behavior of other children, who are not siblings and not necessarily age-mates.”

Peer victimization was measured using peer, self-, and teacher reports, including peer nominations, a four-item self-report victimization scale, and a six-item teacher report victimization scale ( Kochel et al., 2012 ).

Stapinski et al. (2014) used a modified version of the Bullying and Friendship Interview Schedule to assess self-reported peer victimization. This measure includes items on overt victimization, such as threats, physical violence, and relational victimization.

Nonclinical psychotic symptoms are symptoms that do not meet the clinical definition for those psychotic disorders associated with such symptoms.

Peer victimization was measured using a modified six-item version of the Peer Victimization Scale, which asks students to select a statement that is most like them. Higher scores indicated higher levels of peer victimization ( Juvonen et al., 2011 ).

Peer victimization was measured using a 16-item peer nomination interview and a teacher-completed Social Behavior Rating Scale ( Schwartz et al., 2005 ).

Peer victimization is used here to include the broader category of bullying, peer victimization, and bullying behavior.

Psychotic experiences included hallucinations (visual and auditory), delusions (spied on, persecution, thoughts read, reference, control, grandiosity), and experiences of thought interference (broadcasting, insertion, and withdrawal), and any unspecified delusions.

This section is adapted from Rose (2015 , pp. 18-21).

A telomere is the “segment at the end of each chromosome arm which consists of a series of repeated DNA sequences that regulate chromosomal replication at each cell division.” See http://ghr ​.nlm.nih.gov/glossary=telomere [December 2015]. Telomeres are associated with “chromosomal stability” and the regulation of “cells' cellular replicative lifespan” (Kiecolt-Glaser et al., 2011, p. 16).

Peer victimization was measured by a teacher-reported seven-item measure with items measuring broader peer victimization (Hanish et al., 2004).

Peer victimization was measured using the Revised Peer Experiences Questionnaire, which assesses overt, relational, and reputational victimization by peers (McLaughlin et al., 2009).

High risk was defined as a mother who had her first child at age 20 or younger ( Moffitt, 2002 ).

Peer victimization was assessed through teacher, peer, and self-ratings. Children were asked to circle photographs of two classmates who get called names by other children and who are often pushed or hit by other children.

An allele is an alternate form of the same gene. Except for the XY chromosomes in males, human chromosomes are paired, so a cell's genome usually has two alleles for each gene.

The MAOA genotype has been called the “warrior” gene because of its association with aggression in studies using surveys and observations ( McDermott et al., 2009 ).

Peer victimization was measured using a teacher-report 3-item scale that assessed relational victimization in the classroom ( Kretschmer et al., 2013 ).

The FKBP5 rs1360780 gene is associated with a number of different psychological disorders ( Wilker et al., 2014 ).

VanZomeren-Dohm and colleagues (2015 measured peer victimization using the MacArthur Health and Behavior Questionnaire Parent-Form, version 2.1, in which parents reported on their children's experiences of overt peer victimization.

DNA methylation is a heritable epigenetic mark involving the covalent transfer of a methyl group to the C-5 position of the cytosine ring by DNA methyltransferases (a family of enzymes that act on DNA). Cytosine is one of the four bases that occur in varying sequences to form the “code” carried by strands of DNA ( Robertson, 2005 ).

Exposure to violence included domestic violence, bullying victimization, and physical abuse by an adult.

Cumulative violence exposure was measured by an index that summed each type of violence exposure.

• Cite this Page Committee on the Biological and Psychosocial Effects of Peer Victimization: Lessons for Bullying Prevention; Board on Children, Youth, and Families; Committee on Law and Justice; Division of Behavioral and Social Sciences and Education; Health and Medicine Division; National Academies of Sciences, Engineering, and Medicine; Rivara F, Le Menestrel S, editors. Preventing Bullying Through Science, Policy, and Practice. Washington (DC): National Academies Press (US); 2016 Sep 14. 4, Consequences of Bullying Behavior.
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Bullying in School Essay

Introduction, historical roots of bullying, research and statistical reports on bullying in schools.

Bullying can be defined as aggressive behavior that takes into account unwanted and negative actions toward another person or group of people. It is a situation whereby people repeatedly and intentionally use actions or words against others with an aim of causing distress and risks to them. Bullying is mostly evident when there is an imbalance of power among individuals.

For instance, powerful or influential people are said to practice or bully other learners (Olweus, 1993, p. 20). In addition to this, those in power tend to bully others with an aim of making them feel less powerful. Bullying is totally different from conflict though it has been evident that some people bully others because of conflict. The purpose of this study is to explore bullying as it applies in the learning institutions such as schools (Olweus, 1993, p. 45).

There are three different types of bullying namely face-to-face bullying, covert bullying and cyber bullying. Despite their differences, the results are the same that is distress and pain to the people being bullied. Face-to-face bullying is an interesting area of study because it clearly demonstrates bullying in school (Espelage & Swearer 2004, p. 71).

Students tend to think that bullying is harmless by considering it as a part of life or growth for juniors to experience. In contrary, bullying is harmful because it can result to physical harm, loneliness, insecurity and unhappiness to students being bullied. Face-to-face bullying involves actions such as kicking or punching, insulting and name-calling (Smith, Pepler &Rigby, 2004, p. 57).

Students consider bullying as a school culture even though it is contrary to the school rules and regulations of schools. From historical point of view, bullying is often associated with senior students who perceive themselves as being more powerful than juniors.

In regard to this, new comers or first year students are the victim of bullying (McGrath, 2006, p. 23). It has been noted that bullying gains its historical roots from the discipline of the school. This is to mean that the origin of bullying could be traced back to the history of the school based on the aspect of discipline.

In schools whereby discipline is lacking, there are high levels of bullying among students because there are no active rules that can hinder them from bullying each other (Van- Krieken, Habibis, Smith, et al, 2010, p. 34). However, it was further noted that students bully each other because they have been bullied before meaning that they bully others as way of revenge of what happened to them (Rigby, 2007, p. 61).

Through a review of several researches conducted in the U.S. based on bullying in public school it was evident that eighty percent (80%) of public school experience some incidence of bullying among the students for instance, public schools with students of different or varying races such as the black American and the whites (Rigby, 2007, p. 36). In such schools, segregation of students by race is highly witness with white students bullying black American students because of ethnicity background (Beane, 2010, p. 25).

Nearly in every school there is a certain level of bullying because bullying is perceived as a school culture whereby students nickname each other, insult, and punch or kick each other. Statistically, in every 100 fresher’s, at least twenty percent are bullied by senior students. Second year students are said to practice bullying more often than any other students because they tend to think that first years are powerless students in school.

The research findings indicated that schools with high levels of bullying experiences low levels of academic performance among the students. For instance, according to Beane (2010), 90% of bullied students attain poor grades in school because their concentration is interfered with by bullies (Beane, 2010, p. 43).

Bullying in schools is highly associated with the level of discipline practiced in schools meaning that schools with low levels of disciplines provides fertile grounds for aggressive behaviors leading to incidences of bullying. As mentioned within the context of the study, bullying is applicable in every public school in varying levels of implications.

Africa- American students are prone to bullying by the whites students in America public schools. Bullying can only be eliminated if discipline is given a place to play in school but it is quite difficult to clear or do away with bullying in its totality because it is perceived by students as a school culture.

Beane, A. L. (2010). Bullying prevention for schools: A step-by-step guide to implementing a successful anti-bullying program. New Jersey, NJ: John Wiley and Sons.

Espelage, L. D. & Swearer, M. (2004). Bullying in American schools: A social-ecological perspective on prevention and intervention . New York, NY: Routledge.

McGrath, M. J. (2006). School bullying: Tools for avoiding harm and liability . London: Corwin Press.

Olweus, D. (1993). Bullying at school: What we know and what we can do . New York, NY: Wiley-Blackwell.

Rigby, K. (2007). Bullying in schools and what to do about it: Revised and updated . London: Aust Council for Ed Research.

Rigby, K. (2010). Bullying interventions in schools: Six basic approaches . London: Aust Council for Ed Research.

Smith, P., Pepler, D.J &Rigby, K. (2004). Bullying in schools: How successful can interventions be? Cambridge: Cambridge University Press.

Van- Krieken, R., Habibis, D., Smith, P., et al (2010). Sociology. 4 Edn. Sydney: Pearson Education.

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• Bullying in the Schools

Essay on Bullying in Schools

School bullying can be defined as the situation in which one or more students (The Bullies) single out a child (victim) and intend in behavior intended to cause discomfort or harm the child. A bully will repeatedly target the same victim several times. Under all circumstances, bullies have an advantage over the victim as they possess more power. Compared to the victim, bullies usually have physically stronger with a large circle of friends or higher social standing. Bullying can inflict emotional distress, humiliation, and physical harm. More than 95% of learning institutions experience bullying globally. Bullying must be meet a specific rationale to be considered bullying. Such requirements include repetitiveness, recurrent imbalance of power, and provocation. Bullying can occur in schools, on campus, or the outskirts of school, but its setting must have been created within the school. Regardless of the position, all the stakeholders in a school context, such as parents, educators, children, and community members, are required to contribute to the prevention of bullying in schools. School bullying is increasingly becoming a social problem in modern society. Ideally, there are several types of school bullying attached to different causes. The effects of school bullying can be classified in psychological, economical, and academic dimensions.

Types of Bullying in Schools

The common types of bullying in a school setting include verbal, sexual, cyber, psychological, physical, and higher education bullying. Notably, victims in a learning context can experience bullying regardless of age. The aforementioned types of bullying are further classified as either direct or indirect bullying. Direct bullying is defined as an attack that is openly targeted to a victim. Direct bullying is either verbal or physical. Contrary, indirect bullying involves different forms of relational aggression that leads to social isolation through defaming one’s reputation and manipulating the conscience of others into falsehood. Indirect bullying is usually hard and subtle to detect in a school setting (Goodwin et al. 330). If undertaken by a group of bullies, direct and indirect bullying can be referred to as pack bullying. The different types of bullying can be defined either directly or indirectly relative to the implication to the victim.

Physical bullying occurs when there is unwanted physical contact between the victim and the bully. Physical contact can be hand to hand or tripping and throwing items at others that can cause physical harm. The second is emotional bullying. Emotional bullying can be defined as hurting others emotionally by negatively influencing their moods and psyche. The primary examples of emotional bullying include; belittling, spreading false information, and defamation. Verbal bullying can be defined as the usage of slanderous language or statements causing emotional distress to other people. Examples of verbal bullying include harassing, mocking, teasing, and threatening to cause harm. Finally, Cyberbullying is attached to the evolution of the internet and computers. The use of computers in bullying at schoolyards is on the surge. In most instances, schools experience difficulties in controlling cyberbullying as experiences are beyond the school fraternity.

The other common types of school bullying are sexual bullying and higher education bullying. Sexual bullying is either non-physical or physical, grounded on the gender or sexuality of the victim. In most instances, sexual bullying is undertaken by the male gender. The United States department of education reports an average of 60% of expulsions and suspensions from learning institutions attached to sexual bullying (Goodwin et al. 328). In most instances, the young ones are frames into tricks to share their nudes, after which there are forced to fulfill specific sexual demands at the expense of exposure. Higher education bullying occurs at the campus or college level. Around 95% of students have reported having been bullied at the college level. Higher education bullying results in depression and suicide in most cases.

Measures to Control Bullying

The main approaches in controlling bullying in school settings include the implementation of educative programs, creating a positive school climate, engaging parents, encouraging open communication and punishments. These techniques, however, vary depending on the learning level and the prevalence of bullying in the particular period. Education programs involve creating awareness to parents, students, and teachers regarding what constitutes bullying. Educative programs are instrumental in creating insight into the harmful nature of whichever kind of bullying. All the stakeholders within the school fraternity are enrolled in sessions of creating awareness on the signs of bullying and the most appropriate intervention criteria. The most common ways in educating on bullying include role-play, identification and reporting discussions, and other approaches to decline being involved in bullying. Nickerson(19) argued that educative programs are 62% effective in curbing the prevalence of bullying in learning institutions.

Secondly, schools can help in the prevention of bullying by promoting a positive school climate. Schools with a positive climate are presumed to have a healthy development, while the negative school climate results in a surge in bullying cases, unsafe feelings, victimization, and aggression. While the elements of positive school culture vary from norms relative to power, relationships, and feelings, it’s evident that a positive climate is a product of a conscious process that becomes self-reinforcing (Goodwin et al. 330). The main determinants of a positive climate include leadership and integrity in learning institutions. Therefore, the ability to have cognitive leaders is an advantage of coping with bullying in schools.

Third, schools should engage parents. Parents spend most of their time with children at the primary level. While there are many stakeholders involved in the lives of the children, parents play an essential role in understanding their behavior. Engaging parents in bullying scenarios means initiating communication on the progress of the children in terms of behavior and performance. Integration between parents and teachers is essential in providing consistent approaches that help yield a more productive and appropriate behavior (Nickerson 22). Parents can help their children recognize while being bullied by others. However, the approach is not viable in urban schools as parents experience difficulties establishing trust with schools.

Finally, schools should initiate open communication techniques. Open communication is essential in building rapport. Having open communication means that students can disclose their problems to teachers. Open communication helps the teachers gain more insight into existing bullies in the school (Nickerson 20). For instance, classroom meetings in grade 4 will enable teachers to obtain crucial information in enacting more controls to curb bullying in schools. Teachers are expected to listen carefully during the class meetings to avoid inflicting fear on the learners. Students should be assured of confidentiality and privacy of the information obtained as any disclosure might attract further bullying.

Effects of School Bullying 

The effect of school bullying can be categorized in psychological and academic dimensions. Bullying results in poor performance in school. More than 70% of learners subjected to bullying ends up recording a decline in academic performance. The results are more severe at a young age. Bullying would result in fading of interest and participation of learners in school activities as it results in unexplained injuries linked to affecting concentration (Menesini and Christina 246). The impact of bullying on educational performance is increasingly becoming imminent. Bullying installs fear in learners from attending school regularly, thus affecting their consistency and concentration in class. Based on this explanation, it’s evident that bullied students will experience difficulties in achieving their academic goals. Moreover, bullying is linked with an unsafe learning environment that creates a negative climate of fear and insecurities and the perception that teachers do not care about the welfare of learners, thus decline in quality of education.

Secondly, bullying is associated with psychological problems. While bullying to individuals helps them enhance their personality and perceptions as they grow, it’s presumed that bullying can risk an individual developing an antisocial personality disorder linked to committing crimes. Bullying leads to depression, anxiety, and psychosomatic symptoms, which often leads to alcohol and substance abuse by the victims at a later stage in their lives. It’s argued that victims of depression feel free and open to share their experience with others, unlike in bullying, where the victims would choose to shy talking about the feeling in fear of being bullied again. In the short run, bystanders of the bullying experience may develop the fear, guiltiness, and sadness, and if the experience persists, they might get psychologically drained (Sampson). Therefore, the victims of bullying experiences struggle with insomnia, suicidal thoughts, health problems, and depression. Bullying does affect not only the students but also their classmates and family. Feeling powerless, parents and immediate family members might fall victim to depression and emotional distress. Some parents would invest more time in protecting their children, thus affecting them psychologically and economically.

Causes of Bullying

There are numerous causes of school bullying attached to religion, socioeconomic status, race, and gender. Understanding the reasons why students chose to bully their classmates is significant to teachers in combating bullying. The National Center for Educational Statistics report established that 25% of Blacks, 22% of Caucasians, 17% of Hispanics, and 9% of Asian students were bullied in 2017 (Divecha). Some of the students that bully others have higher levels of courage and confidence and can respond aggressively if threatened by the behavior. Students at the college level get bullied on sexual matters. For instance, the subscribers to LGBTQA sexual orientation get bullied based on their decision as gay or lesbians. Moreover, bullying in schools is caused by other factors attached to families. Students from abuse and divorced families are likely to bully others due to jealousy, anger, and despair.

From the above discussion, it’s evident that school bullying in whichever capacity is detrimental to human dignity. School bullying is increasingly becoming a social problem in modern society. Ideally, there are several types of school bullying attached to different causes. The effects of school bullying can be classified in psychological, economical, and academic dimensions. The primary forms of school form such as verbal, sexual, cyber, psychological, physical, and higher education bullying are categorized into direct and indirect bullying. The intervention strategies to curb bullying should involve all the stakeholders, such as parents, teachers, and students. The main approaches in controlling bullying in school settings include implementing educative programs, creating a positive school climate, engaging parents, and encouraging open communication and punishments.

Works Cited

Divecha, Diana. “What Are the Best Ways to Prevent Bullying in Schools?”  Greater Good , https://greatergood.berkeley.edu/article/item/what_are_the_best_ways_to_prevent_bullyi ng_in_schools

Sampson, Rana. “Center for Problem-Oriented Policing.” Arizona State University,  https://popcenter.asu.edu/content/bullying-schools-0

Menesini, Ersilia, and Christina Salmivalli. “Bullying in schools: the state of knowledge and effective interventions.”  Psychology, health & medicine  22.sup1 (2017): 240-253.

Goodwin, John, et al. “Bullying in schools: an evaluation of the use of drama in bullying prevention.” Journal of Creativity in Mental Health 14.3 (2019): 329-342.

Nickerson, Amanda B. “Preventing and intervening with bullying in schools: A framework for evidence- based practice.”  School Mental Health  11.1 (2019): 15-28.

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Conclusion: Implications and Addressing School Bullying and Inequality

• First Online: 22 December 2020

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• Anthony A. Peguero   ORCID: orcid.org/0000-0002-4541-865X 4 &
• Jun Sung Hong   ORCID: orcid.org/0000-0003-2816-9900 5  

Part of the book series: Springer Series on Child and Family Studies ((SSCFS))

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In the concluding Chap. 9 , we discuss why ameliorating violence and victimization should be a priority. Of course, addressing bullying victimization that occurs within schools for all youth is paramount toward sustaining a system that is supposed to facilitate educational progress and sustainability. There is a persistent history of disparities linked to socioeconomic and social status, family cohesion and interactions, sexual orientation, gender identity, and gender expression, race, ethnicity, immigration, and religion, and disabilities and special health needs in the U.S. school system. The social problem of bullying within U.S. schools is both complex and diverse. It is clear that the sources and factors associated with the vulnerability and marginalization of youth to being victimized at school presented in this book also intersect. Although homes, schools, and neighborhoods may never be completely bully-free environments, there are several ways to assist students in breaking the bullying and peer victimization cycles. The information presented in this book is also one calling for advocacy, which will suggest that if policymakers, school administrators, and community stakeholders are seeking to address and ameliorate bullying within schools, it is vital to consider the significance of various forms of social inequality.

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Espelage, D. L. (2016). Sexual orientation and gender identity in schools: A call for more research in school psychology—No more excuses. Journal of School Psychology, 54 , 5–8.

Article   PubMed   Google Scholar  

Birkett, M., Espelage, D. L., & Koenig, B. (2009). LGB and questioning students in schools: The moderating effects of homophobic bullying and school climate on negative outcomes. Journal of Youth and Adolescence, 38 (7), 989–1000.

Article   PubMed   PubMed Central   Google Scholar  

Kahle, L. (2017). Are sexual minorities more at risk? Bullying victimization among lesbian, gay, bisexual, and questioning youth. Journal of Interpersonal Violence , 0886260517718830.

Google Scholar  

Kahle, L. (2018). Feminist and queer criminology: A vital place for theorizing LGBTQ youth. Sociology Compass, 12 (3), e12564.

Article   Google Scholar  

Pascoe, C. J. (2011). Dude, you’re a fag: Masculinity and sexuality in high school . University of California Press.

Meyer, E. (2008). A feminist reframing of bullying and harassment: Transforming schools through critical pedagogy. McGill Journal of Education/Revue des sciences de l’éducation de McGill, 43 (1), 33–48.

Peguero, A. A., & Bondy, J. M. (2020). The importance of immigration with future research about school safety. Race and Justice, 10 (3), 247–268.

Schwartz, A. E., Stiefel, L., & Rothbart, M. W. (2016). Do top dogs rule in middle school? Evidence on bullying, safety, and belonging. American Educational Research Journal, 53 (5), 1450–1484.

Zembylas, M. (2010). Teachers’ emotional experiences of growing diversity and multiculturalism in schools and the prospects of an ethic of discomfort. Teachers and Teaching: Theory and Practice, 16 (6), 703–716.

Zembylas, M. (2012). Transnationalism, migration and emotions: Implications for education. Globalisation, Societies and Education, 10 (2), 163–179.

Espelage, D. L. (2014). Ecological theory: Preventing youth bullying, aggression, and victimization. Theory Into Practice, 53 (4), 257–264.

Gonzales, R. G. (2015). Lives in limbo: Undocumented and coming of age in America . Berkeley, CA: University of California Press.

Book   Google Scholar  

Foucault, M. (1977). Discipline and punish: The birth of the prison. Vintage.

Simon, J. (2007). Governing through crime: How the war on crime transformed American democracy and created a culture of fear . Oxford University Press.

Crenshaw, K., Ocen, P., & Nanda, J. (2015). Black girls matter: Pushed out, overpoliced, and underprotected . New York, NY: Center for Intersectionality and Social Policy Studies, Columbia University.

Morris, M. (2016). Pushout: The criminalization of black girls in schools . New York: The New Press.

Portillos, E. L., González, J. C., & Peguero, A. A. (2012). Crime control strategies in school: Chicanas’/os’ perceptions and criminalization. The Urban Review, 44 (2), 171–188.

Rios, V. M. (2011). Punished: Policing the lives of black and Latino boys . NYU Press.

Rios, V. M. (2017). Human targets: Schools, police, and the criminalization of Latino youth . University of Chicago Press.

Noguera, P. A. (2009). The trouble with black boys:... And other reflections on race, equity, and the future of public education . San Francisco, CA: Jossey-Bass.

Peguero, A. A., & Shekarkhar, Z. (2011). Latino/a student misbehavior and school punishment. Hispanic Journal of Behavioral Sciences, 33 (1), 54–70.

Muschert, G. W., & Peguero, A. A. (2010). The Columbine effect and school anti-violence policy. Research in Social Problems and Public Policy, 17 , 117–148.

Kupchik, A. (2010). Homeroom security: School discipline in an age of fear . New York: NYU Press.

Addington, L. A. (2009). Cops and cameras: Public school security as a policy response to Columbine. American Behavioral Scientist, 52 (10), 1426–1446.

Muschert, G. W., Henry, S., Bracy, N. L., & Peguero, A. A. (2013). Responding to school violence: Confronting the Columbine effect . Boulder, CO: Lynne Rienner Publishers.

Bradshaw, C. P. (2013). Preventing bullying through positive behavioral interventions and supports (PBIS): A multitiered approach to prevention and integration. Theory Into Practice, 52 (4), 288–295.

Bradshaw, C. P., Koth, C. W., Bevans, K. B., Ialongo, N., & Leaf, P. J. (2008). The impact of school-wide positive behavioral interventions and supports (PBIS) on the organizational health of elementary schools. School Psychology Quarterly, 23 (4), 462.

Bradshaw, C. P., Koth, C. W., Thornton, L. A., & Leaf, P. J. (2009). Altering school climate through school-wide positive behavioral interventions and supports: Findings from a group-randomized effectiveness trial. Prevention Science, 10 (2), 100.

Simonsen, B., Sugai, G., & Negron, M. (2008). Schoolwide positive behavior supports: Primary systems and practices. Teaching Exceptional Children, 40 (6), 32–40.

Sprague, J. R., & Golly, A. (2005). Best behavior: Building positive behavior support in schools . Longmont, CO: Sopris-West.

Sugai, G., & Horner, R. (2010). School-wide positive behavior support: Establishing a continuum of evidence based practices. Journal of Evidence-Based Practices for Schools, 11 (1), 62–83.

Peguero, A. A., & Bondy, J. M. (2015). Schools, justice, and immigrant students: Segmented assimilation, race, ethnicity, gender, and perceptions of fairness and order. Teachers College Record, 117 (7), n7.

Peguero, A. A., Bondy, J. M., & Shekarkhar, Z. (2017). Punishing Latina/o youth: School justice, fairness, order, dropping out, and gender disparities. Hispanic Journal of Behavioral Sciences, 39 (1), 98–125.

Shedd, C. (2015). Unequal city: Race, schools, and perceptions of injustice . Russell Sage Foundation.

Gottfredson, D. C. (2001). Schools and delinquency . New York: Cambridge University Press.

Gottfredson, D. C. (2017). Prevention research in schools: Past, present, and future. Criminology & Public Policy, 16 (1), 7–27.

Gottfredson, G. D., Gottfredson, D. C., Payne, A. A., & Gottfredson, N. C. (2005). School climate predictors of school disorder: Results from a national study of delinquency prevention in schools. Journal of Research in Crime and Delinquency, 42 (4), 412–444.

Payne, A. A. (2004). School community and disorder: Communal schools, student bonding, delinquency, and victimization . El Paso, TX: LFB Scholarly Publishing.

Payne, A. A. (2008). A multilevel analysis of the relationships among communal school organization, student bonding, and delinquency. Journal of Research in Crime and Delinquency, 45 (4), 429–455.

Payne, A. A., Gottfredson, D. C., & Gottfredson, G. D. (2003). Schools as communities: The relationships among communal school organization, student bonding, and school disorder. Criminology, 41 (3), 749–778.

Kozol, J. (2005). The shame of the nation: The restoration of apartheid schooling in America . Broadway Books.

Kozol, J. (2012). Savage inequalities: Children in America’s schools . Broadway Books.

Lareau, A. (2011). Unequal childhoods: Class, race, and family life . Univ of California Press.

Lewis, A. E. (2003). Race in the schoolyard: Reproducing the color line in school 2003b New Brunswick . New Brunzwick, NJ: Rutgers University Press.

Lewis, A. E., & Diamond, J. B. (2017). Despite the best intentions: How racial inequality thrives in good schools . Oxford University Press.

Kao, G., Vaquera, E., & Goyette, K. (2013). Education and immigration . John Wiley & Sons.

Lee, S. J. (2009). Unraveling the" model minority" stereotype: Listening to Asian American youth . New York: Teachers College Press.

Lee, J., & Zhou, M. (2015). The Asian American achievement paradox . New York: Russell Sage Foundation.

Peguero, A. A. (2008). Is immigrant status relevant in school violence research? An analysis with Latino students. Journal of School Health, 78 (7), 397–404.

Peguero, A. A. (2009). Victimizing the children of immigrants: Latino and Asian American student victimization. Youth & Society, 41 (2), 186–208.

Peguero, A. A. (2013). An adolescent victimization immigrant paradox? School-based routines, lifestyles, and victimization across immigration generations. Journal of Youth and Adolescence, 42 (11), 1759–1773.

Peguero, A. A. (2008). Bullying victimization and extracurricular activity. Journal of School Violence, 7 (3), 71–85.

Espelage, D. L., & Swearer, S. M. (2010). Bullying in North American schools . Routledge.

Olweus, D. (1993). Bullying at school: What we know and what we can do . Oxford, UK: Blackwell Publishers.

Olweus, D., Limber, S., & Mihalic, S. (1999). Bullying prevention program: Blueprints for violence prevention, book nine . Boulder, CO: Center for the Study and Prevention of Violence.

Farrington, D. P., & Ttofi, M. M. (2009). School-based programs to reduce bullying and victimization. Campbell systematic reviews, 5 (1), i–148.

Ttofi, M. M., & Farrington, D. P. (2011). Effectiveness of school-based programs to reduce bullying: A systematic and meta-analytic review. Journal of Experimental Criminology, 7 (1), 27–56.

Mishna, F. (2008). An overview of the evidence on bullying prevention and intervention programs. Brief Treatment and Crisis Intervention, 8 (4), 327.

Hong, J. S. (2009). Feasibility of the Olweus bullying prevention program in low-income schools. Journal of School Violence, 8 (1), 81–97.

Peguero, A. A. (2012). Schools, bullying, and inequality: Intersecting factors and complexities with the stratification of youth victimization at school. Sociology Compass, 6 (5), 402–412.

Safran, E. R. (2007). Bullying behavior, bully prevention programs, and gender. Journal of Emotional Abuse, 7 (4), 43–67.

Vaillancourt, T., McDougall, P., Hymel, S., Krygsman, A., Miller, J., Stiver, K., & Davis, C. (2008). Bullying: Are researchers and children/youth talking about the same thing? International Journal of Behavioral Development, 32 (6), 486–495.

Gonzalez, T. (2012). Keeping kids in schools: Restorative justice, punitive discipline, and the school to prison pipeline. JL & Educ., 41 , 281.

Lockhart, A., Zammit, L., Charboneau, R., Owens, R., & Ross, R. (2005). Restorative justice: Transforming society . Inclusion Press.

Stinchcomb, J. B., Bazemore, G., & Riestenberg, N. (2006). Beyond zero tolerance: Restoring justice in secondary schools. Youth Violence and Juvenile Justice, 4 (2), 123–147.

Pavelka, S. (2013). Practices and policies for implementing restorative justice within schools. The Prevention Researcher, 20 (1), 15–18.

Morrison, B. E., & Vaandering, D. (2012). Restorative justice: Pedagogy, praxis, and discipline. Journal of School Violence, 11 (2), 138–155.

Payne, A. A., & Welch, K. (2013). Restorative justice in schools: The influence of race on restorative discipline. Youth & Society, 47 (4), 539–564.

Miller, H. V., Ripepi, M., Ernstes, A. M., & Peguero, A. A. (2020). Immigration policy and justice in the era of COVID-19. American Journal of Criminal Justice , 1–17.

Viner, R. M., Russell, S. J., Croker, H., Packer, J., Ward, J., Stansfield, C., Booy, R. et al. (2020). School closure and management practices during coronavirus outbreaks including COVID-19: A rapid systematic review. The Lancet Child & Adolescent Health 4 .

Tessler, H., Choi, M., & Kao, G. (2020). The anxiety of being Asian American: Hate crimes and negative biases during the COVID-19 pandemic. American Journal of Criminal Justice , 1–11.

Taylor, K.-Y. (2016). From #BlackLivesMatter to black liberation . Haymarket Books.

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Peguero, A.A., Hong, J.S. (2020). Conclusion: Implications and Addressing School Bullying and Inequality. In: School Bullying. Springer Series on Child and Family Studies. Springer, Cham. https://doi.org/10.1007/978-3-030-64367-6_9

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9 facts about bullying in the U.S.

Many U.S. children have experienced bullying, whether online or in person. This has prompted discussions about schools’ responsibility to curb student harassment , and some parents have turned to home-schooling or other measures to prevent bullying .

Here is a snapshot of what we know about U.S. kids’ experiences with bullying, taken from Pew Research Center surveys and federal data sources.

Pew Research Center conducted this analysis to understand U.S. children’s experiences with bullying, both online and in person. Findings are based on surveys conducted by the Center, as well as data from the Bureau of Justice Statistics, the National Center for Education Statistics and the Centers for Disease Control and Prevention. Additional information about each survey and its methodology can be found in the links in the text of this analysis.

Bullying is among parents’ top concerns for their children, according to a fall 2022 Center survey of parents with children under 18 . About a third (35%) of U.S. parents with children younger than 18 say they are extremely or very worried that their children might be bullied at some point. Another 39% are somewhat worried about this.

Of the eight concerns asked about in the survey, only one ranked higher for parents than bullying: Four-in-ten parents are extremely or very worried about their children struggling with anxiety or depression.

About half of U.S. teens (53%) say online harassment and online bullying are a major problem for people their age, according to a spring 2022 Center survey of teens ages 13 to 17 . Another 40% say it is a minor problem, and just 6% say it is not a problem.

Black and Hispanic teens, those from lower-income households and teen girls are more likely than those in other groups to view online harassment as a major problem.

Nearly half of U.S. teens have ever been cyberbullied, according the 2022 Center survey of teens . The survey asked teens whether they had ever experienced six types of cyberbullying. Overall, 46% say they have ever encountered at least one of these behaviors, while 28% have experienced multiple types.

The most common type of online bullying for teens in this age group is being called an offensive name (32% have experienced this). Roughly one-in-five teens have had false rumors spread about them online (22%) or were sent explicit images they didn’t ask for (17%).

Teens also report they have experienced someone other than a parent constantly asking them where they are, what they’re doing or who they’re with (15%); being physically threatened (10%); or having explicit images of them shared without their consent (7%).

Older teen girls are especially likely to have experienced bullying online, the spring 2022 survey of teens shows. Some 54% of girls ages 15 to 17 have experienced at least one cyberbullying behavior asked about in the survey, compared with 44% of boys in the same age group and 41% of younger teens. In particular, older teen girls are more likely than the other groups to say they have been the target of false rumors and constant monitoring by someone other than a parent.

They are also more likely to think they have been harassed online because of their physical appearance: 21% of girls ages 15 to 17 say this, compared with about one-in-ten younger teen girls and teen boys.

White, Black and Hispanic teens have all encountered online bullying at some point, but some of their experiences differ, the spring 2022 teens survey found. For instance, 21% of Black teens say they’ve been targeted online because of their race or ethnicity, compared with 11% of Hispanic teens and 4% of White teens.

Hispanic teens are the most likely to say they’ve been constantly asked where they are, what they’re doing or who they’re with by someone other than a parent. And White teens are more likely than Black teens to say they’ve been targeted by false rumors.

The sample size for Asian American teens was not large enough to analyze separately.

During the 2019-2020 school year, around two-in-ten U.S. middle and high school students said they were bullied at school . That year, 22% of students ages 12 to 18 said this, with the largest shares saying the bullying occurred for one day only (32%) or for between three and 10 days (29%), according to the most recent available data from the Bureau of Justice Statistics (BJS) and the National Center for Education Statistics (NCES).

Certain groups of students were more likely to experience bullying at school. They include girls, middle schoolers (those in sixth, seventh or eighth grade), and students in rural areas.  

The most common types of at-school bullying for all students ages 12 to 18 were being made the subject of rumors (15%) and being made fun of, called names or insulted (14%).

The classroom was the most common location of bullying that occurred at school in 2019-2020, the BJS and NCES data shows. This was the case for 47% of students ages 12 to 18 who said they were bullied during that school year. Other frequently reported locations included hallways or stairwells (39%), the cafeteria (26%) and outside on school grounds (20%).

Fewer than half (46%) of middle and high schoolers who were bullied at school in 2019-2020 said they notified a teacher or another adult about it, according to the BJS and NCES data. Younger students were more likely to tell an adult at school. Around half or more of sixth, seventh and eighth graders said they did so, compared with 28% of 12th graders.

Students who reported more frequent bullying were also more likely to notify an adult at school. For instance, 60% of those who experienced bullying on more than 10 days during the school year told an adult, compared with 35% of those who experienced it on one day.

In 2021, high schoolers who are gay, lesbian or bisexual were about twice as likely as their heterosexual counterparts to say they’d been bullied, both at school and online, according to the Centers for Disease Control and Prevention . In the 12 months before the survey, 22% of high school students who identify as gay, lesbian or bisexual – and 21% of those who identify as questioning or some other way – said they were bullied on school property. That compares with 10% of heterosexual students. The data does not include findings for transgender students.

The trend is similar when it comes to electronic bullying through text or social media: 27% of high school students who identify as lesbian, gay or bisexual say they experienced this in the 12 months before the survey, as did 23% of those who identify as questioning or some other way. That compares with 11% of those who identify as heterosexual.

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Avoiding the "Last Straw" in Cases of Bullying

Preventing adolescent victims who are bullied from becoming perpetrators..

Posted April 22, 2024 | Reviewed by Davia Sills

• How to Handle Bullying
• Find counselling to support kids or teens
• Teens who become bullies were often bullied themselves.
• However, not all victims of bullies become perpetrators.
• A new study suggests that the way a bullied teen copes can either increase or decrease their risk of violence.
• Early intervention can help the bullied victim get the help they need before they become violent.

Many teenagers are bullied at some point. In response, some seek revenge and become bullies themselves. But why some and not others? A new study by researchers in China suggests the victim's internal world differentiates those who seek revenge from those who don't. Their research indicates that two thought patterns, in particular, have a massive impact on how adolescents interpret and respond to abusive peers.

One of these thought patterns is a hostile attribution bias , i.e., the tendency to assume that when an interpersonal situation is ambiguous, the default interpretation is that the other person's intentions are hostile. For example, if a peer doesn't respond to a greeting in the hallway, a teen with hostile attribution bias might automatically assume the peer is deliberately ignoring them. But what if the nonresponsive peer didn't hear them or was distracted? A teen who has developed a hostile attribution bias is hypervigilant; they see threats everywhere. And they base their reactions on these assumptions without checking them out.

In fact, how a victim interprets being bullied may wield as much influence as how often the mistreatment occurs. Sure, being frequently bullied ups the odds for a desire for revenge, but a hostile attribution bias explains part of this link; in the minds of these victims, bystanders are viewed as collaborators and innocuous encounters are interpreted as persecution.

The second cognitive style is a specific type of rumination . We all mentally replay upsetting events. But there's a difference between revisiting a distressing event to understand it better or deal with it more effectively and mentally rehashing the specific details and reliving their emotions. It's the latter type—this angry rumination—that fuels the desire for retaliation.

If we drill down a little deeper, we can examine who is more likely to develop these potentially dangerous coping styles. What leads a victim to violence is due to a complex interplay of individual and environmental factors, but we have identified some risk factors for these thought patterns:

• Teens with pre-existing aggressive tendencies, impulsivity, or conduct problems
• Bullied teens who lack social support and are socially awkward
• Teens who have witnessed or experienced violence at home
• The absence of protective factors, such as abstract thinking abilities, empathy, and self-regulation skills
• School climate and whether adults effectively intervene

Connecting the Dots

So, how do we use these research findings to make schools safer? Let's pretend that a school counselor is concerned that a bullied teen might become violent to get revenge. Perhaps he has made concerning remarks to a peer, or a teacher has noticed an increasingly belligerent attitude in class. They call in a threat assessment professional to conduct an interview. Typical questions would likely focus on general violence risk—specific revenge plans, access and familiarity with weapons, mental health symptoms, criminal or violence history, previous communication about and strategies used to stop bullying and their effectiveness, etc. (Of course, others would be interviewed as well.)

These findings suggest that exploring this teen's inner world will also yield valuable information. It may be helpful not only to ask how often they think about their mistreatment (how many times a day or week) but what they think about it. When they think about it, what do they focus on? How long do they think about it (a few minutes, an hour, several hours, more)? Do they pop up even when you're trying to focus on something else? If they try, can they turn off those thoughts? Do they feel more agitated and on edge after thinking about it, or does it calm them down? Do they ever fantasize about getting revenge? If so, what do they imagine doing? If not, what would change this answer from a no to a yes?

Anyone who has evaluated a teenager for any aggressive behavior problem knows it's a dynamic process; violence risk can quickly change. This is why it's so important to divert an angry but not presently dangerous adolescent toward therapeutic resources that can build rapport, express empathy, and guide them toward healthier, nonviolent coping mechanisms. They can also monitor behavior as well as environmental triggers that are most likely to tempt a bullied teen to become violent, such as:

• A new, severe bullying incident that feels like the "last straw"
• Seeing their bullies receive acclaim or reward, which feels profoundly unjust
• Feeling publicly humiliated by their bullies
• Perceiving that adults have failed to protect them or take the bullying seriously
• Reaching a point of hopelessness where they believe violence is the only solution

The Bottom Line

Becoming a bully is not an inevitable outcome of being bullied. Most victimized teens can work through their understandable anger without resorting to violence themselves. They can avoid or break free from a victim-to-bully cycle.

This starts with a careful evaluation of the teen's unique risk and protective factors to gauge their potential for violence, as well as developing an appropriate intervention plan in collaboration with the school counselor, parents, and other support providers. Intervening early ups the odds that therapeutic options are still available, where the therapist takes the student's distress seriously and provides the comprehensive, compassionate care they need to recover and thrive.

Joni E. Johnston , Psy.D , is a clinical/forensic psychologist, private investigator, author, and host of the YouTube channel and podcast "Unmasking a Murderer."

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6 Ways Schools Are Managing Students’ Cellphone Use

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A flurry of school districts across the country are tightening cellphone restrictions, because they believe students’ misuse of the devices has negatively affected their behavior and ability to learn.

In 2015, 66 percent of schools in the United States prohibited non-academic use of cellphones during school hours, according to the National Center for Education Statistics . By 2020, that percentage had jumped to 77 percent.

Many educators blame students’ cellphone use for being the top distraction in schools and classrooms . The constant use of the devices has also been linked to students’ worsening mental health .

The issue has caught the attention of federal and state policymakers, too. Some states—such as California, Florida, Indiana, and Tennessee—have passed laws allowing schools to restrict cellphone use. A handful of other states are considering passing similar laws. Congressional lawmakers have also introduced legislation that would require a federal study on the effects of cellphone use on students’ mental health and academic performance.

Liz Kolb, a clinical professor of education technologies and teacher education at the University of Michigan, said it’s unlikely that all 50 states will pass laws restricting students’ cellphone use, “but we’re seeing a lot more [movement] at the individual school level, where they’re trying to figure out policies that make sense [for their communities].”

At the district level, these restrictions vary widely. Some districts restrict student cellphone use anywhere and any time during the school day. Some allow use of the devices during lunch and in the hallways. And others haven’t placed any restrictions at all, often because of parent and student pushback.

Even in districts where there’s a ban, “there’s a lot of nuance” in how schools are addressing it, Kolb said. “In order for a full school ban to be effective, you really have to have strong leadership supporting the staff in enforcing it.”

Some of those nuances include exceptions for students who have a documented need to have their digital devices for health reasons, such as checking blood glucose levels if a student has diabetes. Teachers also have the flexibility to allow students to use their cellphones in class if they are needed for instructional purposes.

Here are six different policy approaches districts are putting in place to address concerns about student cellphone use:

1. Cellphones are restricted for all students, regardless of grade level

In Florida’s Orange County district , all students are prohibited from using their cellphones and other wireless communication devices, such as smartwatches, during school hours—meaning from the first bell to the dismissal bell, these devices must be silenced and put away in their bags. If a student is caught using a phone during the school day, the device will be confiscated and returned to the student at the end of the day. Depending on the circumstances of the violation, a student could also get detention or be suspended.

Flint schools in Michigan also prohibit all students, regardless of grade level, from using cellphones or other personal electronic devices. If a student is caught using a phone, it will be confiscated and returned to the student’s parent or caretaker.

Some districts provide technological solutions, such as pouches, to lock and store students’ phones during the school day. In other districts, educators have found creative ways to separate students from their phones, such as using over-the-door shoe holders where students place their phones during class.

2. Cellphones restricted only for elementary students, more flexible for middle and high school students

While restrictions on the use of cellphones and other two-way communication devices exist for all students in the Wauwatosa district in Wisconsin , there are more flexible rules for middle and high school students. Cellphones are prohibited all day for elementary students, but middle and high school students can use their phones before and after school, between class periods, during lunch, and in free periods. Teachers and principals have discretion for imposing consequences for misuse.

3. Cellphones are prohibited for elementary and middle school students, but more flexible for high school students

Elementary and middle school students in Virginia’s Rockingham district are prohibited from using personal electronic devices during the school day, while high school students may use their devices during lunch, study hall, advisory periods if permitted by a teacher and principal, and in between classes.

4. Cellphones are restricted only in classrooms, locker rooms, and bathrooms

Other districts, such as Richmond schools in Wisconsin, have restrictions on cellphone use only in certain areas of schools, such as classrooms, locker rooms, and bathrooms—to prevent bullying or sharing of inappropriate images, according to some district policies.

5. Cellphones restricted only in classrooms

Some restrictions are centered around classroom time only and allow students to use their phones outside of the classroom. In the Brush school district in Colorado , for instance, students aren’t allowed to have their phones out during instructional hours but can use them any other time. If a student is caught with a phone when they’re not allowed to have it, parents can either come to school to collect the phone or they can let the school keep the phone until the end of the day.

6. Cellphone restrictions are left up to each school

There are also districts, such as Meriden in Connecticut and Minnetonka in Minnesota, that don’t have districtwide restrictions, but instead have guidelines that schools can choose to follow.

For instance, in Meriden, the guidelines recommend elementary students keep their phones in their bags the whole school day; middle school students keep their phones in their lockers but can use them during lunch; and to let high school students have access to their phones all day but they must be turned off and out of sight during class time.

Other districts, such as Pawtucket in Rhode Island , allow principals or teachers to implement their own school or classroom rules around cellphones, as long as there’s a clear plan for allowing students to use them in case of emergencies.

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