OBSESSIVE-COMPULSIVE DISORDER

Although neuroimaging has a limited role in the diagnostic assessment of obsessive-compulsive disorder (OCD), neuroimaging research has cont ributed crucial information regarding the pathophysiology of OCD and r elated diseases. OCD may be one of a spectrum of disorders that all in volve corticostriatal pathology, in which the clinical presentation re flects the topography of dysfunction within the striatum. Structural n euroimaging studies of OCD have indicated volumetric abnormalities in the caudate nucleus. Functional imaging studies of OCD have shown incr eased activity in the corticostriatal pathway involving anterior orbit ofrontal cortex and the caudate nucleus, both at rest and during sympt om provocation, which is attenuated following effective treatment. Par alimbic elements, such as the anterior cingulate and posterior orbitof rontal cortex, may play a role in mediating anxiety or arousal nonspec ifically. Taken together, these imaging data support the ''striatal to pography'' model of OCD and suggest directions for future research, fo cusing on processes involving anterior orbitofrontal cortex and the ca udate nucleus.