Functional neuroimaging studies in untreated OCD consistently demonstrate increased metabolic activity in which region, a finding that normalises after successful treatment with either SSRIs or cognitive behaviour therapy?

• A Hippocampus
• B Primary motor cortex
• C Orbitofrontal cortex ✓
• D Cerebellar vermis

Explanation

PET and SPECT studies show hypermetabolism in the orbitofrontal cortex, anterior cingulate cortex, and head of the caudate nucleus in OCD, forming the basis of the cortico-striato-thalamo-cortical loop model. Successful treatment with SSRIs or CBT reduces this orbitofrontal and caudate hyperactivity toward normal levels. The primary motor cortex, hippocampus, and cerebellar vermis are not part of the reproducible imaging signature of OCD, which eliminates the remaining options.

Reference: Kaplan and Sadock's Synopsis of Psychiatry, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.