PET imaging in obsessive compulsive disorder with and without depression.

Obsessive compulsive disorder (OCD) is a classic psychoneurosis which is frequently complicated by major depression. Recent positron emission tomography neuroimaging studies, when taken in the context of a variety of other data, implicate a brain dysfunction involving the orbital prefrontal cortex and the striatum in the mediation of OCD behaviors and those of the related Gilles de la Tourette's syndrome. The anterolateral prefrontal cortex is implicated in the secondary major depressions often complicating OCD.