Prefrontal blood flow dysregulation in drug naive ADHD children without structural abnormalities

Recent studies suggest a role for prefrontal cortex abnormalities in the pa thogenesis of attention deficit/hyperactivity disorder (ADHD). We evaluated young drug-naive ADHD outpatients without MRI structural abnormalities to detect prefrontal cortex regional cerebral blood flow (rCBF) functional dys regulation; correlation between age and rCBF; and correlation between sympt oms profile and rCBF. Functional brain activities (i.e. rCBF), neuropsychol ogical attention performance and symptom profile were evaluated respectivel y by single photon emission computerized tomography (SPECT) scan, Stroop Te st and the Child Attention Problem Rating Scale. There was a decreased rCBF in the left dorso lateral prefrontal cortex (DLPFC) compared to the right DLPFC of the subjects. In addition, there were positive correlations betwee n age and relative rCBFs of the dorsolateral and orbital prefrontal cortex, and negative correlations between age and absolute rCBFs of the dorsolater al and orbital prefrontal cortex. Finally, higher levels of right relative rCBF and lower levels of left relative rCBF were predictors of higher sever ity of clinical symptom expression and neuropsychological attention impairm ent. The results of this study highlight the role of the DLPFC blood flow i mpairment in the pathogenesis of ADHD even in young subjects without struct ural abnormalities.