Executive function and attention deficit hyperactivity disorder: stimulantmedication and better executive function performance in children

Background. Executive function deficits have been reported repeatedly in ch ildren with Attention Deficit Hyperactivity Disorder (ADHD). Stimulant medi cation has been shown to be effective in improving cognitive performance on most executive function tasks, but neuropsychological tests of executive f unction in this population have yielded inconsistent results. Methodologica l limitations may explain these inconsistencies. This study aimed to measur e executive function in medicated and non-medicated children with ADHD by u sing a computerized battery, the Cambridge Neuropsychological Test Automate d Battery (CANTAB), which is sensitive to executive function deficits in ol der patients with frontostriatal neurological impairments. Methods. Executive function was assessed in 30 children with ADHD: 15 were stimulant medication naive and 15 were treated with stimulant medication. T hese two groups were compared to 15 age, sex and IQ matched controls. Results. The unmedicated children with ADHD displayed specific cognitive im pairments on executive function tasks of spatial short-term memory, spatial working memory, set-shifting ability and planning ability. Impairments wer e also seen on spatial recognition memory and delayed matching to sample, w hile pattern recognition memory remained intact. The medicated children wit h ADHD were not impaired on any of the above executive function tasks excep t for deficits in spatial recognition memory. Conclusions. ADHD is associated with deficits in executive function. Stimul ant medication is associated with better executive function performance. Pr ospective follow-up studies are required to examine these effects.