EFFECTS OF ACUTE STIMULANT MEDICATION ON CEREBRAL METABOLISM IN ADULTS WITH HYPERACTIVITY

Recent work in our laboratory has demonstrated both global and regiona l reductions in cerebral glucose metabolism in adult subjects with att ention-deficit hyperactivity disorder (ADHD). The purpose of the prese nt study was to examine the effects of an acute dose of stimulant medi cation on cerebral metabolism in adults with ADHD using positron emiss ion tomography with fluorodeoxyglucose-18 as the tracer. Each subject underwent scanning twice, once off-drug and again after receiving a si ngle oral dose of either dextroamphetamine (0.25 mg/kg) or methylpheni date (0.35 mglkg). Subjects completed behavioral self-report measures before and after the scan and performed an auditory continuous perform ance task during the tracer uptake period. Neither drug changed global metabolism. Both drugs increased systolic blood pressure, and dextroa mphetamine improved performance on the auditory attention task. Each s timulant produced a differential pattern of increases and decreases in regional metabolism throughout the regions of interest that were samp led. Rather than increasing glucose utilization in specific brain regi ons with lowered metabolic rates in adults with ADHD, stimulants may a ct by altering glucose use throughout the brain.