Effect of mental disorders on the association between bullying, suicidality and self-harm among Australian adolescents: A mediation analysis using data from a nationwide survey

Abstract Background Recent research has depicted that both traditional and cyber bullying victimization report serious mental health issues, particularly suicidal and non-suicidal self-harm in adolescents. However, the little is known about the mechanism underlying the correlation between bullying and risk behaviours – suicidality and self-harm. This study aimed to examine the effect of bullying victimization on suicidal and non-suicidal self-harm, and the mediating effect of mental disorders (major depressive disorder, ADHD, conduct disorder and anxiety disorder) on the relationship between bullying victimization, suicidality and self-harm among adolescents. Methods Data for this study came from the Young Minds Matter: the second Australian Child and Adolescent Survey of Mental Health and Wellbeing and Youth dataset, which is a cross-sectional nationwide survey. A total of 2166 adolescents aged 12–17 years (M = 14.83; SD = 1.61; 52.2% boys) were analyzed. Baron and Kenny’s approach with regression analysis was employed to test the mediation effect of each mental disorder on the association between traditional and cyber bullying victimization, suicidality and self-harm. Further, the Sobel test was used to statistically assess whether the indirect effects of bullying victimization on suicidality and self-harm were significant via mental disorder. Results Overall, 622 (28.7%) and 255 (11.8%) of adolescents reported traditional and cyberbullying victimization, respectively. The analysis showed that victims of both bullying incurred a significantly higher risk of suicidality and self-harm among adolescents. The effect of both bullying victimization on suicidality and self-harm was mediated by major depressive disorder after adjusting for the effect of potential sociodemographic characteristics, substance use, sedentary activities. While anxiety disorder only mediated the relationship between traditional bullying, and suicidality and self-harm. ADHD and conduct disorder had no mediating effect. Conclusions Depression and anxiety disorder plays a mediating role in the association between bullying victimization, suicidal and self-harming behaviour. Thus, addressing such mental disorders among bullying victims is worthwhile to prevent suicidality and non-suicidal self-harm, and ultimately suicide.