Recently there have been a lot of advances in understanding Obsessive Compulsive Disorder (OCD) with the help of investigations like Magnetic Resonance Image (MRI) and Positron Emission Tomography PET scans.
MRI studies comparing volumes of specific brain regions in patients with OCD have often yielded conflicting and inconsistent results. Brain regions of interest have included the head of the Caudate Nucleus (CN) the orbitofrontal cortex and the anterior cingulate gyrus. With respect to the caudate nucleus (CN) especially, studies have found increases, decreases and no change in volume between OCD patients and healthy controls on (MRI) scans. The source of this apparent discrepancy in the volumetric literature may be methodological in nature. Furthermore it has been suggested that the heterogeneity of OCD a disease with several unique classifications and subtypes can be responsible for the inconsistent volume differences among various structures as reported in the literature.
PET examines cerebral metabolism using flurodeoxyglucose. PET studies on patients with OCD confirm that elevated glucose metabolism occurs in the bilateral thalamus, caudate and OFC regions. In an another study of the patients who check, hypermetabolism was found in the putamen/globus pallidus, the thalamus and the right inferior frontal cortex; in those who wash, the greatest activation was identified in the OFC the Cingulate Gyrus and the ventrolateral prefrontal cortex.