Impaired school functions varied in ASD youths with different characteristics. Youths with autism spectrum disorder (ASD) encounter varying levels and domains of impaired performance at schools, such as lower academic performance, negative attitude toward school work, fewer reciprocal friendships, and more behavioral problems. Our results indicate that ASD youths without intellectual disability had better academic performance, but worse attitude toward school than those with intellectual disability. Co-occurrence with ADHD is associated with school dysfunction. In summary, intelligence and comorbid ADHD influences several domains of school functions.

Childhood attention-deficit/hyperactivity disorder (ADHD) and comorbid oppositional defiant disorder/conduct disorder (ODD/CD) are associated with negative school outcomes. The study aimed to examine the impact of ADHD and ODD/CD on various school functions. 395 youths with ADHD (244 with ADHD + ODD/CD and 151 with ADHD only) and 156 controls received semi-structured psychiatric interviews. School functions were assessed and compared between each group with a multiple-level model. The results showed that youths with ADHD had poorer performance across different domains of school functioning. Youths with ADHD + ODD/CD had more behavioral problems but similar academic performance than those with ADHD only. The multiple linear regression models revealed that ADHD impaired academic performance while ODD/CD aggravated behavioral problems. Our findings imply that comorbid ODD/CD may specifically contribute to social difficulties in youths with ADHD. Measures of early detection and intervention for ODD/CD should be conducted to prevent adverse outcomes.