Autism and Convictions for Violent Crimes: Population-Based Cohort Study in Sweden

Objective: Recent systematic reviews have highlighted that the relationship between autism and violent offending is still unclear, but some cases have received extensive media scrutiny. We investigated whether autism is associated with convictions for violent crimes, and studied the associated risk and protective factors. Method: We analyzed data from the Stockholm Youth Cohort, a total population-based record-linkage cohort in Stockholm County comprising 295,734 individuals followed up between 15 and 27 years of age. Of these, 5,739 individuals had a recorded autism diagnosis. The main outcome measure was a conviction for violent crimes identified using the Swedish National Crime Register. Results: Individuals with autism, particularly those without intellectual disability, initially appeared to have a higher risk of violent offending (adjusted relative risk = 1.39, 95% CI = 1.23-1.58). However, these associations markedly attenuated after co-occurring attention-deficit/hyperactivity disorder (ADHD) or conduct disorder were taken into account (adjusted relative risk = 0.85, 95% CI = 0.75-0.97). Among individuals with autism, male sex and psychiatric conditions were the strongest predictors of violent criminality, along with parental criminal and psychiatric history and socioeconomic characteristics. There was some evidence that a delayed diagnosis of autism was associated with a greater risk of violent crime. Better school performance and intellectual disability appeared to be protective. Conclusion: An initially observed association between autism and violent crimes at a population level was explained by comorbidity with ADHD and conduct disorder. Better understanding and management of comorbid psychopathology in autism may potentially help preventive action against offending behaviors in people with autism.