ffect of Methylphenidate on Executive Functioning n Adults with Attention-Deficit/Hyperactivity isorder: Normalization of Behavior but Not Related rain Activity

ackground: We examined the effect of prolonged methylphenidate (MPH) treatment on the functional neuroanatomy of executive unctioning in adult men with attention-deficit/hyperactivity disorder (ADHD). ethods: Positron emission tomography with [O] water measured alterations of regional cerebral blood flow (rCBF) during the aced Auditory Serial Addition Task and a control task in 10 ADHD and 11 normal control men. Attention-deficit/hyperactivity isorder men were imaged unmedicated and after a clinically optimal dose of MPH for 3 weeks. esults: Methylphenidate improved ADHD task performance, reduced rCBF in the prefrontal cortex (PFC), and increased rCBF in the ight thalamus and precentral gyrus. Comparisons between the ADHD and normal control groups showed that normal control articipants exhibited greater anterior cingulate cortex and temporal gyrus rCBF than ADHD participants under both conditions. xecutive functioning was associated with greater subcortical (basal ganglia and cerebellar vermis) activation in the ADHD than ormal control group under both conditions. onclusions: Methylphenidate does not normalize task-related activity in ADHD. Task-related rCBF decreases in the PFC may be due o improved filtering out of task-irrelevant stimuli by way of MPH-mediated dopamine release in the PFC.