Abstract
OBJECTIVE: Response inhibition impairment is one of the most characteristic symptoms of attention-deficit/hyperactivity disorder (ADHD). Thus functional magnetic resonance imaging (fMRI) during a Go/No-Go task seems to be an ideal tool for examining neuronal correlates of inhibitory control deficits in ADHD. Prior studies have shown frontostriatal abnormalities in children and adolescents. The aim of our study was to investigate whether adults with ADHD would still show abnormal brain activation in prefrontal brain regions during motor response inhibition tasks. METHODS: fMRI was used to compare brain activation in 15 untreated adult patients with ADHD and 15 healthy reference volunteers during performance of a Go/No-Go task. RESULTS: In contrast to various other studies with children and adolescents with ADHD, we found no significant difference in the activity of anterior cingulate cortex (ACC) or other frontostriatal structures between ADHD and healthy adults. Significantly enhanced activity was found in the parietal cortex, which is known to play an important role in building up attention. CONCLUSION: We hypothesize that the enhanced activity is due to the ability of adult ADHD patients to compensate their deficits for a short time, which is demonstrated in our study by equal task performance in both groups.