The neurobiology of attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder is a childhood psychiatric disorde r characterized by inattention, impulsivity, and overactivity. Considerable research has focused on the neurobiological substrates of this disorder. A lthough the specific nature of the brain dysfunction remains elusive, progr ess has been made and several models of the underlying pathophysiology have been suggested. Research in the fields of neuropsychology, neuroimaging, n eurochemistry, and molecular genetics, which points to a multifactorial eti ology for the disorder, is reviewed. While several inconsistencies exist ac ross studies, evidence supports dysfunction of fronto-striatal dopaminergic and noradrenergic circuits with resultant executive deficits in cognitive functioning.