Effects of Methylphenidate Discontinuation on Cerebral Blood Flow in Prepubescent Boys with Attention Deficit Hyperactivity Disorder

Methylphenidate (MPH) is an effective symptomatic treat-ment of attention deficit hyperactivity disorder (ADHD), but the mechanisms of its therapeutic action have not been fully elucidated. To address this issue, we assessed the effects of discontinuation of chronic MPH treatment on regional cere-bral blood flow (rCBF) in ADHD patients. Methods: Twenty-two prepubescent boys with ADHD (age range, 8.2–11.5 y) and 7 healthy volunteers were studied with SPECT on and off MPH. Their rCBF data were automatically normalized to whole-brain counts and coregistered with standard anatomic space. rCBF changes were evaluated with statistical para-metric mapping based on voxel-by-voxel ANOVA. Results: When the subjects were not taking MPH, rCBF was higher in the motor, premotor, and the anterior cingulate cortices (Brodmann’s areas 4, 6, and 32). Conclusion: Brief discon