Abstract
The mean diagnosis age of autism was about 5 years in Taiwan. Whether the delayed diagnosis of autism (≥ 6 years) was associated with parental severe mental disorders remained unknown. The parents of 22,859 autistic individuals and 228,590 age- and sex-matched nonautistic individuals were assessed for the presence of severe mental disorders (schizophrenia, bipolar disorder, major depressive disorder, alcohol use disorder, and substance use disorder). The timing of autism diagnosis was classified into three age categories: < 6 years, 6-11 years, and ≥ 12 years. Logistic regression models were used to examine associations between parental severe mental disorders and these age categories of autism diagnosis. Parental schizophrenia and substance use disorders were associated with the delayed diagnosis of autism, both diagnosis at ≥ 12 years (odds ratio [OR]: 2.14; 1.57) and at 6-11 years (1.87; 1.38). Parental bipolar disorder and major depressive disorder were also associated with the delayed diagnosis of autism, especially diagnosis at 6-11 years (OR 1.98; 1.86). Our findings underscore the need for clinicians to monitor the neurodevelopmental conditions of offspring born to parents with severe mental disorders during the early stages of their life.