VOLUMETRIC MRI ANALYSIS COMPARING SUBJECTS HAVING ATTENTION-DEFICIT HYPERACTIVITY DISORDER WITH NORMAL CONTROLS

Objective: To test by MRI-based morphometry the a priori hypotheses th at developmental anomalies exist in attention-deficit hyperactivity di sorder (ADHD) in left caudate and right prefrontal/frontal/ and/or pos terior parietal hemispheric regions, in accord with neurochemical, neu ronal circuitry and attentional network hypotheses, and prior imaging studies. Design: Case-control study. Setting: Academic medical center, Participants: Fifteen male subjects with ADHD without comorbid diagno ses (aged 12.4 +/- 3.4 years) and 15 male normal controls (aged 14.4 /- 3.4), group-matched for age, IQ, and handedness. Main outcome measu res: Global and hemispheric regional volumes (in cm(3)) of cerebral he mispheres, cortex, white matter, ventricles, caudate, lenticulate, cen tral gray nuclei, insula, amygdala, and hippocampus. Results: Despite similar hemispheric volumes, ADHD subjects had smaller volumes of (1) left total caudate and caudate head (p < 0.04), with reversed asymmetr y (p < 0.03); (2) right anterior-superior (frontal) region en bloc(p < 0.03) and white matter (p < 0.01); (3) bilateral anterior-inferior re gion en bloc(p < 0.04); and (4) bilateral retrocallosal (parietal-occi pital) region white matter (p < 0.03). Possible structural correlates of ADHD response to stimulants were noted in an exploratory analysis, with the smallest and symmetric caudate, and smallest left anterior-su perior cortex volumes found in the responders, but reversed caudate as ymmetry and the smallest retrocallosal white matter volumes noted in t he nonresponders, Conclusions, This study is the first to report local ized hemispheric structural anomalies in ADHD, which are concordant wi th theoretical models of abnormal frontal-striatal and parietal functi on, and with possible differing morphologic substrates of response to stimulant medication.