Self-harm (suicidal ideation and attempts; non-suicidal self-injuries behavior) peaks in adolescence and early-adulthood, with rates higher for women than men. Young women with childhood psychiatric diagnoses appear to be at particular risk, yet more remains to be learned about the key predictors or mediators of self-harm outcomes. Our aims were to examine, with respect to self-harm-related outcomes in early adulthood, the predictive validity of childhood response inhibition, a cardinal trait of attention-deficit hyperactivity disorder (ADHD), as well as the potential mediating effects of social preference and peer victimization, ascertained in early adolescence. Participants were an ethnically and socioeconomically diverse sample of 228 girls with and without ADHD, an enriched sample for deficits in response inhibition. Childhood response inhibition (RI) predicted young-adult suicide ideation (SI), suicide attempts (SA), and non-suicidal self-injury (NSSI), over and above full-scale IQ, mother's education, household income, and age. Importantly, teacher-rated social preference in adolescence was a partial mediator of the RI-SI/SA linkages; self-reported peer victimization in adolescence emerged as a significant partial mediator of the RI-NSSI linkage. We discuss implications for conceptual models of self-harm and for needed clinical services designed to detect and reduce self-harm.
Keywords: Attention-deficit/hyperactivity disorder (ADHD); Females; Longitudinal; Peer victimization; Response inhibition; Self-harm.