Neuropsychological correlates of childhood attention-deficit/hyperactivity disorder: explainable by comorbid disruptive behavior or reading problems?

Questions remain as to whether neuropsychological processing deficits associated with child attention-deficit/hyperactivity disorder (ADHD) are accounted for by co-occurring disorders, especially in clinical samples. The authors examined ADHD and comorbid oppositional defiant, conduct, and reading disorders. Boys with ADHD displayed hypothesized deficits on effortful neuropsychological tasks regardless of categorical or dimensional control of comorbid antisocial behavior problems. The same result held when reading problems were controlled, although boys with ADHD plus reading disorder (n = 16) exhibited specific impairment on linguistic output tasks. Simultaneous control of reading and behavior problems yielded the same result. Overall, results suggest that in a clinical sample, difficulties on effortful neuropsychological tasks that require planning or controlled motor output pertain at least in part to ADHD and are not fully accounted for by comorbid conditions.