MRI scans from 19 children aged 7 to 18 years, with recent onset obsessive-compulsive disorder (OCD), untreated with psychotropic drugs, and 19 matched controls, were analyzed for striatal volume at Western Psychiatric Institute, University of Pittsburgh, PA. Patients with OCD had significantly smaller putamen and total striatal volumes (7% reduction) and larger third ventricles than controls. Prefrontal cortical, white matter, lateral ventricular, and intracranial volumes were not altered. Reduced striatal volume was inversely correlated with severity of OCD symptoms, but not with illness duration or age of onset. Males and females were equally involved. 
COMMENT. This study confirms the striatal pathology in children with obsessive-compulsive disorder, and emphasizes the role of the putamen in OCD. The findings were not related to prior medication effects or comorbid illness such as depression or anxiety.
Oculomotor response inhibition abnormalities in OCD are reported by the above authors in a study of 18 untreated children, aged 8 to 16 years, compared to 18 controls. The ability to suppress behavioral responses related to prefrontal cortical function was reduced in OCD patients.