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 attention-deficit/hyperactivity disorder (ADHD) classified by type (combined [CT] or predominantly inattentive [IT]) and comorbidity with oppositional defiant disorder (ODD) and reading disorder (RD).

Method: The Wisconsin Card Sorting Test (WCST) and Tower of Hanoi (TOH) were administered to 28 community volunteers and 359 children (7.5-13.5 years old) divided into ADHD types, 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 ADHD/CT patients made more nonperseverative errors than ADHD/IT children. ODD was associated with moderately better TOH performance and RD with excessive rule breaks.

Conclusions: Executive functioning deficits were found for only ADHD/CT children and were independent of comorbidity with RD or ODD.