Background: Little is known about the predictive association between childhood bullying behavior with depression and suicidal ideation at age 18.
Methods: The sample included 2348 boys born in 1981. Information about bullying was gathered at the age of 8 from self, parent and teacher's reports. Depression and suicidal ideation were assessed during the Finnish military call-up examination.
Results: Based on regression models, boys who were bullies frequently, but not merely sometimes, were more likely to be severely depressed and to report suicidal ideation compared to boys who were not bullies. When controlling for depression at age 8 the association between frequent bullying and severe depression was maintained but the association with suicidal ideation became non-significant. Boys who were only victimized were not more likely to be depressed or to report suicidal ideation at age 18. Boys who were frequently both bullies and victims were found to be at risk for later depression.
Limitations: Our finding can only be generalized to boys who were involved in bullying at elementary school age. Data at age 18 was based only on self-reports and the bullying/victimization questions were very general.
Conclusions: Childhood bullying behavior is a risk factor for later depression. Screening and intervention for bullying behavior in the early school years is recommended to avoid subsequent internalizing problem in late adolescence.