Changes in regional cerebral blood flow (rCBF) with age were studied by SPECT in 29 drug-naive patients with attention deficit hyperactivity disorder (ADHD) (24 boys, 5 girls; age 7-13) and 12 with complex partial epilepsy as controls, at NIMH International Mental Health Program, Istanbul; and University of Ankara Medical School, Ankara, Turkey. The prefrontal cortex rCBF during resting conditions showed increased lateralization from right to left with age in ADHD subjects, and compared to controls, ADHD was associated with lower right prefrontal/frontal and higher parietal rCBF. These differences were greater in subjects older than 7 years. The left hemisphere dominance in the prefrontal cortex increased significantly with age in ADHD subjects, whereas the control group showed no significant correlations between age and asymmetry of rCBF. 
COMMENT. The lower right prefrontal and frontal cerebral blood flow in ADHD subjects correlates with previous reports of an abnormal right frontal development on functional imaging studies (Castellanos FX et al. 1996; Ped Neur Briefs Aug 1996). Decreased volume of prefrontal cortex, caudate nucleus, and globus pallidus on the right side point to a dysfunction of the prefrontal-striatal circuits in ADHD.