A study of 2,341 children, aged 13-19 in New York looked at bullying and its potential association with depression and suicidal behaviour among adolescents. About 20% of the sample reported that they were victims of bullying in school and another 10% said that they were bullied outside school. 25% of students said that they bullied other students in school and 15% said that they bullied people outside school. Children who were frequent victims of bullying in school were five times as likely to have suicidal thoughts and four times as likely to have attempted suicide than other children. However, those children who engaged in bullying behaviour were three times as likely to have suicidal thoughts and to have made suicide attempts than other children. Students who were both victims and perpetrators of bullying were at the highest risk for depression and suicidal behaviour.
Klomek, A.B. ... [et al] - Bullying, depression and suicidality in adolescents. Journal of the American Academy of Child and Adolescent Psychiatry 2007, 46, 40-49