Neural mechanisms underlying the therapeutic actions of guanfacine treatment in youth with ADHD: a pilot fMRI study.

Twenty-five youth with attention-deficit/hyperactivity disorder (ADHD) were scanned with functional magnetic resonance imaging (fMRI) while performing a Go/No-go task before and after 6-8 weeks of randomized once-daily treatment with either the α₂A-adrenergic receptor agonist guanfacine or placebo. Clinical improvement was greater for guanfacine than placebo and was differentially associated with reduced activation for guanfacine compared with placebo in the right midcingulate cortex/supplementary motor area and the left posterior cingulate cortex.