Autistic Traits and Suicidal Thoughts, Plans, and Self-Harm in Late Adolescence: Population-Based Cohort Study

OBJECTIVE: To examine the hypothesis that autism spectrum disorders (ASD) diagnosis and traits in childhood are associated with suicidal thoughts, plans and self-harm at 16 years, and that any observed associations are explained by depression at 12 years. METHOD: We examined associations between ASD diagnosis and 4 dichotomized ASD traits (social communication, pragmatic language, repetitive behavior, and sociability) with suicidal and nonsuicidal self-harm, suicidal thoughts, and suicidal plans at age 16 years in 5,031 members of the United Kingdom−based birth cohort study the Avon Longitudinal Study of Parents and Children. We assessed whether any associations were explained by depressive symptoms in early adolescence measured by the Short Moods and Feelings Questionnaire at 12 years. RESULTS: Children with impaired social communication had a higher risk of self-harm with suicidal intent (relative risk [RR] = 2.14, 95% CI = 1.28–3.58), suicidal thoughts (RR = 1.42, 95% CI = 1.06–1.91), and suicidal plans (RR = 1.95, 95% CI = 1.09–3.47) by age 16 years as compared to those without. There was no evidence for an association between ASD diagnosis and outcomes, although these analyses were imprecise because of small numbers. There was also no evidence of an association between other autism traits and the outcomes. Approximately 32% of the total estimated association between social communication impairment and self-harm was explained by depressive symptoms at 12 years. CONCLUSION: Social communication impairments are an important autistic trait in relation to suicidality. Early identification and management of depression may be a preventative mechanism, and future research identifying other potentially modifiable mechanisms may lead to interventions against suicidal behavior in this high-risk group.