Substance use in adulthood following adolescent self-harm: a population-based cohort study

OBJECTIVE: To determine whether adolescents who self-harm are at increased risk of heavy and dependent substance use in adulthood. METHOD: Fifteen-year prospective cohort study of a random sample of 1943 adolescents recruited from secondary schools across the state of Victoria, Australia. Data pertaining to self-harm and substance use was obtained at seven waves of follow-up, from mean age 15.9 years to mean age 29.1 years. RESULTS: Substance use and self-harm were strongly associated during the adolescent years (odds ratio (OR): 3.3, 95% CI 2.1-5.0). Moreover, adolescent self-harmers were at increased risk of substance use and dependence syndromes in young adulthood. Self-harm predicted a four-fold increase in the odds of multiple dependence syndromes (sex- and wave-adjusted OR: 4.2, 95% CI: 2.7-6.6). Adjustment for adolescent anxiety/depression attenuated but did not eliminate most associations. Adolescent substance use confounded all associations, with the exception of multiple dependence syndromes, which remained robustly associated with adolescent self-harm (fully adjusted odds ratio: 2.0, 95% CI: 1.2-3.2). CONCLUSION: Adolescent self-harm is an independent risk factor for multiple dependence syndromes in adulthood. This level of substance misuse is likely to contribute substantially to the premature mortality and disease burden experienced by individuals who self-harm.