Attention-deficit/hyperactivity disorder (ADHD) and conduct disorder overlap behaviorally, clinically, and cognitively. An important question of potential future clinical relevance is whether these two overlapping disorders are mediated by similar or distinct underlying brain substrates. This article reviews the modern neuroimaging literature on brain structure, function, and connectivity in both disorders, shaping out commonalities and differences. Findings show that ADHD is characterized predominantly by abnormalities in inferior frontal, striatal, parietotemporal, and cerebellar regions and networks that mediate "cool"-cognitive, i.e., inhibitory, attention and timing functions associated with the disorder. Conduct disorder, by contrast, has consistently been associated with abnormalities of the "hot" paralimbic system that regulates motivation and affect, comprising lateral orbital and ventromedial prefrontal cortices, superior temporal lobes, and underlying limbic structures, most prominently the amygdala. Direct comparisons in functional imaging show that these associations of cool inferior fronto-striato-cerebellar dysfunction in ADHD and of hot orbitofrontal-paralimbic dysfunction in conduct disorder are disorder-specific. There is, hence, evidence for dissociated underlying pathophysiologies for these two disorders that may have implications for future anatomy-based differential diagnosis and prevention and intervention.

Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.