The effect of childhood adverse experiences on the development of self-harm and suicidality: a prospective cohort study

Background: Exposure to adverse childhood experiences (ACEs) has been shown to predict both self-harm and suicidal ideation in young people. However, few longitudinal studies have examined the relationship between ACEs and self-harm and suicidal ideation emerging during adolescence. The aim of this study was therefore to examine the longitudinal relationship between ACEs at baseline, and new incidence of self-harm and suicidality over two years among Australian adolescents, and to identify moderators of these relationships. Method: Australian school-based adolescents (N = 6388, M = 13.9, 48.9 % female) completed baseline surveys between August 2019 to December 2021, and follow-up surveys 12 and 24 months later. Surveys were completed at school. Binary mixed models were used to examine the relationship between total ACE exposure at baseline and new incidence of both self-harm and suicidal ideation at follow-up. The models included demographic, school, social and mental-health related variables. Results: Total ACE exposure at baseline significantly predicted new incidence of self-harm and suicidal ideation at follow-up. Although gender and sexuality both uniquely predicted new incidence of self-harm, neither variable moderated the relationship between ACEs and self-harm. The association between total ACEs and self-harm may be mediated by baseline depression, anxiety, and distress. Conclusion: Interventions and policies that prevent the occurrence of ACEs need to be developed and/or upscaled, given the contribution of ACEs to self-harm and suicidality among young people. Interventions targeting young people who have been exposed to ACEs should aim to prevent the development of psychological disorders and ensure that young people are supported on a family and individual level.