ORIGINAL ARTICLE Common and Unique Therapeutic Mechanisms of Stimulant and Nonstimulant Treatments for Attention-Deficit/Hyperactivity Disorder

is a highly prevalent and impairing psychiatric disorder that affects both children and adults. There are Food and Drug Administration–approved stimulant and nonstimu-lant medications for treating ADHD; however, little is known about the mechanisms by which these different treatments exert their therapeutic effects. Objective: To contrast changes in brain activation re-lated to symptomatic improvementwith use of the stimu-lant methylphenidate hydrochloride vs the nonstimu-lant atomoxetine hydrochloride. Design: Functional magnetic resonance imaging be-fore and after 6 to 8 weeks of treatment with methylphe-nidate (n=18) or atomoxetine (n=18) using a parallel-groups design