How do victims of bullying develop depression? Testing interpersonal style to explain the victimization-depression link.

This study tested to what extent the relation between bullying victimization and future symptoms of depression could be explained by victims being more hostile and less assertive than non-involved individuals. Data came from waves 2-4 of the Dutch TRacking Adolescents' Individual Lives Survey (TRAILS). Participants' bullying experiences were assessed at age 13, interpersonal style at age 16, and depression symptoms at age 19. Mediation analyses were performed primarily on 274 self-reported victims and 1498 non-involved peers. Self-reported victims had an increased risk for depression symptoms. About a third of that risk could be explained by victims' hostile style, which was also higher than those of non-involved peers. Although victims also reported lower levels of assertiveness than non-involved peers, this interpersonal style did not mediate the link between bullying victimization and depression. Our findings suggest that high hostility, but not low assertiveness, partly explains the increased depression risk of self-reported victims. Therefore, interventions could focus on addressing hostility, to help reduce the likelihood that adolescents who have experienced bullying victimization will have more interpersonal conflicts and mental health problems in the future. Supplementary materials also include analyses for bullies and bully-victims, and for peer-reported measures.