Mental health disorders and suicide risk among autistic children, adolescents and adults: a population-based study using linked administrative data.

Abstract

Autistic people face elevated mental health risks, yet few population-based studies have quantified these risks across developmental stages. We examined the prevalence and relative risk of physician-diagnosed mental health disorders and suicide attempts among autistic individuals in the province of Manitoba, Canada, using linked administrative health data. We conducted a whole-population cohort study using provincial health records from 2018 to 2022. Autistic individuals were identified using a validated case definition and compared to all other Manitobans without autism. We assessed five-year prevalence and sex- and age-adjusted relative risks of attention-deficit hyperactivity disorder (ADHD), conduct disorder, mood/anxiety disorders, schizophrenia, substance use disorders, and suicide attempts across three age groups (6-12, 13-17, and 18-45 years) using regression models. Autistic people had substantially higher prevalence of all examined mental health disorders (except substance use disorder) and significantly elevated relative risks across every age group we examined. Compared to non-autistic individuals, autistic people had higher risks of ADHD (age- and sex-adjusted relative risk [aRR] 5.24, 95% confidence interval [CI] 4.82-5.70), conduct disorder (aRR 5.96, 95% CI 4.61-7.70), mood/anxiety disorders (aRR 2.00, 95% CI 1.89-2.12), schizophrenia (aRR 9.82, 95% CI 8.94-10.78), and attempted suicide (aRR 3.14, 95% CI 2.31-4.27). The study cohort included n = 317,073 males and n = 314,261 females. Autistic males (n = 4523) had higher risk of being diagnosed with ADHD (aRR 1.39, 95% CI 1.35-1.43), conduct disorder (aRR 1.54, 95% CI 1.34-1.78), and schizophrenia (aRR 1.83, 95% CI 1.71-1.96), whereas autistic females (n = 1377) had higher risk of mood/anxiety disorders (aRR 1.96, 95% CI 1.87-2.00) and attempted suicide (aRR 2.22, 95% CI 2.00-2.44). Autistic individuals experience disproportionate mental health challenges, including suicide risk, across their life course. These findings demonstrate the urgent need for sex-specific, autism-informed mental health strategies, early routine screening, and specialized clinical training to improve diagnostic assessment and care delivery in universal health systems. We gratefully acknowledge the support of the Azrieli Foundation, the National Centre for Autism Collaboration, the Autism Alliance of Canada, and the Canadian Institutes of Health Research.