Functional brain imaging of OCD patients showed abnormalities in the orbitofrontal cortex (OFC; a brain region responsible for decision making which is linked to multiple regions related to emotion, reward, and cognition) — specifically, abnormal metabolism both during baseline and symptoms. Do these abnormalities result from different connections of the OFC or from an abnormality of the OFC itself?
This study by Dr. Szeszko and his team investigated this concern using structural magnetic resonance imaging (MRI) scans of 26 OCD patients and 26 healthy controls, and followed the course of OFC sulci (grooves in the brain) to find the boundaries of the OFC in each participant. The hypothesis was that OCD patients would have a reduced OFC volume. The results confirmed this by demonstrating that patients with OCD had smaller bilateral orbitofrontal and amygdala (a brain region related to emotion and fear) volumes that healthy controls, as well as more symmetry in the hippocampus-amygdala region These results show that regions related to decision making, cognition, and emotion are impacted by OCD, and are associated with changes in brain regions.
*Szeszko, P.R., Robinson, D., Alvir, J.M.J., Bilder, R.M., Lencz, T., Ashtari, M., Wu, H., & Bogerts, B. (1999). Orbital frontal and amygdala volume reductions in obsessive-compulsive disorder. Archives of General Psychiatry, 56, 913-919. doi:10.1001/archpsyc.56.10.913