Comparison of Attention-Deficit Hyperactivity Disorder in Typically Developing Children and Children with Down Syndrome

Objective: This study aimed to evaluate attention-deficit hyperactivity disorder (ADHD) symptom patterns among children with Down syndrome (DS) with or without ADHD and typically developing (TD) children with ADHD. Methods: Parents and teachers rated symptoms of inattention, hyperactivity, and general behavioral concerns for 22 children with DS and comorbid diagnoses of ADHD (DS + ADHD), 66 gender-matched and age-matched children with DS with no diagnosis of ADHD (DS - ADHD), and 66 gender-matched and age-matched TD children with ADHD (TD + ADHD). Children with DS were recruited from the community. TD children with ADHD were recruited from a specialty clinic evaluating for ADHD. Results: Parents tended to report higher scores of inattention and hyperactivity for TD children with ADHD compared with children with DS and no ADHD. Although mean ADHD symptom summary scores were not significantly different in DS + ADHD and DS - ADHD, specific parent-report items (e.g., distractibility and being "on the go") did tend to differentiate these groups. By contrast, teachers tended to report higher inattention and hyperactivity scores for DS + ADHD compared with both DS - ADHD and TD + ADHD. Specific teacher-reported items tending to differentiate DS + ADHD and DS - ADHD included difficulties following through on tasks, avoiding tasks, leaving one's seat, and excessive talking. Conclusion: Variability in response patterns between parent and teacher reports for children with and without DS highlights the need to evaluate ADHD symptoms across environments. Our findings also suggest specific items that may particularly be helpful in distinguishing children with DS who do and do not have ADHD, although replication is needed.