The co-occurrence of autistic spectrum disorder and schizophrenia: A nationwide population-based study

Although the co-occurrence of autistic spectrum disorder (ASD) and schizophrenia have been previously reported, the scope and magnitude of this comorbidity across large samples have not been sufficiently established. This study was aimed to assess the co-occurrence between schizophrenia and ASD in a large dataset, and to examine its predominance across different age and sex groups. Schizophrenia patients and age and sex frequency controls (n = 49,334) were assessed for the prevalence of autism spectrum disorder. The sample was stratified by age and sex, and co-occurrence was assessed using univariate and multivariate logistic regressions. Results indicated that schizophrenia was associated with ASD (OR = 7.01, 95%CI 2.98-16.43, p < .0001) across all age groups aside from 50 to 70 years. This association was significant among male participants (OR = 11.69, 95%CI 3.59-38.01, p < .0001) but not among female participants (OR = 2.33, 95%CI 0.60-9.03, p = .21). These findings indicate a large overlap between schizophrenia and ASD, and point to the need to expand the understanding of the potential mediating mechanisms of this co-occurrence.