Attention-deficit/hyperactivity disorder: perspectives from neuroimaging.

Attention-deficit/hyperactivity disorder (ADHD) is a common childhood behavioral disorder most often characterized by inattentiveness, impulsivity, and hyperactivity. Current etiologic theories suggest that ADHD stems from abnormalities in dopaminergic and possibly noradrenergic brainstem nuclei that act to regulate a cortico-striato-thalamo-cortical network, believed to be critical for executive functions and the regulation of behavioral responses such as arousal, attention, and inhibition. Noninvasive structural and functional neuroimaging techniques provide a new avenue for exploring the validity of these theories. Despite their limitations, neuroimaging studies have provided a unique and otherwise inaccessible, biological perspective of ADHD. Collectively, the studies reviewed here reveal that dysfunction in arousal, behavioral inhibition, and attention associated with ADHD may result from structural abnormalities in frontostriatal regions that in turn result in diminished activity essential for normal function.