Executive functioning deficits in attention-deficit/ hyperactivity disorder are independent of oppositional defiant or reading disorder

Objective: To evaluate deficits of executive functions in children with att ention-deficit/hyperactivity disorder (ADHD) classified by type (combined [ CT] or predominantly inattentive [IT]) and comorbidity with oppositional de fiant disorder (ODD) and reading disorder (RD), Method: The Wisconsin Card Sorting Test (WCST) and Tower of Hanoi (TOH) were administered to 28 commun ity volunteers and 359 children (7.5-13.5 years old) divided into ADHD type s, RD, and ODD. Results: ADHD/CT children solved fewer puzzles and violated more rules on the TOH than ADHD/IT or non-ADHD subjects. On the WCST there were no differences between diagnostic samples in perseverativeness, but A DHD/CT patients made more nonperseverative errors than ADHD/IT children. OD D was associated with moderately better TOH performance and RD with excessi ve rule breaks. Conclusions: Executive functioning deficits were found for only ADHD/CT children and were independent of comorbidity with RD or ODD.