Hippocampal shape deformity analysis in obsessive-compulsive disorder.

Abnormalities of orbital prefrontal cortex and caudate nuclei have, thus far, been the main findings regarding the pathophysiology of obsessive-compulsive disorder (OCD). On the other hand, neuroimaging studies have failed to reach a consensus with regard to the issue of hippocampal abnormalities in OCD patients. Shape analysis may facilitate a resolution of the discordance among these former studies by detecting local structural changes, thus enhancing power to discriminate structural differences. It has been suggested that neural circuitry interconnecting brain areas may critically influence the shape of neuroanatomical structures, serving as a rationale for better sensitivity of shape analysis compared to volume analysis, especially in detecting abnormalities of neural circuitry. Shape analysis of the hippocampus was performed in 22 matched pairs of OCD patients and normal control subjects. As a result, we observed a bilateral hippocampal shape deformity including the most prominent characteristic of downward displacement of the head. The hippocampal structural alteration observed in this study indicates that this structure may play a role in the pathophysiology of OCD. Also, further considering the hippocampal neural connections specific to its surface topography, these surface deformities may reflect developmental alterations in these patients with regard to the neural circuitry involving hippocampus.