Bullying others increases the risk of developing mental health problems and vice versa

Bullying is defined as any unwanted aggressive behavior by another youth or group of youths, who are not siblings or dating partners, and is repeated multiple times or highly likely to be repeated. In the U.S., it has been estimated that between 18-31 percent of youths are involved in bullying.

"While it is well documented that bullying victimization is associated with immediate and life-long mental health problems, no studies to date have examined the hypothesis that the relationship between bullying perpetration and mental health problems may be bidirectional," said Marine Azevedo Da Silva, PhD, postdoctoral researcher at Columbia Mailman School of Public Health.

The researchers analyzed data from 13,200 youths aged 12 to 17 years in the nationally representative Population Assessment of Tobacco and Health survey to study the bidirectional association between bullying perpetration and internalizing problems. Among them, 79 percent reported they never bullied others, 11 percent reported having bullied others over a year ago, and 10 percent reported having bullied others in the past year. When bullying perpetration was considered as a past month measure, 16 percent reported having bullied others over a month ago, and 5 percent reported having bullied others in the past month.

When the researchers examined the relationship between bullying perpetration as a predictor of internalizing problems, they found that youths who reported being the perpetrators of bullying were more likely to develop a moderate to high incidence of mental health problems compared to those who reported not perpetrating bullying. On the other hand, they found that adolescents who experienced moderate to high internalizing problems had increased risk of bullying others compared to those who reported no or low incidence of having mental health problems.

"The study we designed allowed us to show that the association is likely to be bidirectional between bullying perpetration and internalizing problem. However, it is important to point out that the methods of assessment -- including definitions, question wording, and self-report -- could overestimate or underestimate the prevalence of bullying and in turn, influence the strength of association between bullying perpetration and internalizing problems.," observed Marine Azevedo Da Silva.

"Our findings provide an important extension to previous literature, and indicate that bullying behaviors prevention and intervention strategies among youth should consider how to take into account and handle negative feelings and mental health problems" said Silvia Martins, MD, PhD, director of the Substance Abuse Epidemiology Unit of the Department of Epidemiology and senior author.