Brain structural abnormalities in obsessive-compulsive disorder: converging evidence from white matter and grey matter

Introduction: Specific cortico-striato-thalamic circuits are hypothesised to underlie the aetiology of obsessive-compulsive disorder (OCD). However, findings from neuroimaging studies have been inconsistent. In the current study, we attempted to provide a complete overview of structural alterations in OCD by conducting signed differential mapping (SDM) meta-analysis on grey matter and white matter studies of patients with OCD based on voxel-based morphometry (VBM) studies and diffusion tensor imaging (DTI) studies.

Methods: Fifteen VBM and seven DTI case-control studies were included in this meta-analysis. SDM meta-analyses were performed to assess grey matter volume and white matter integrity changes in OCD patients and healthy controls.

Results: We found that OCD patients had smaller grey matter volume than health controls in the frontal eye fields, medial frontal gyrus and anterior cingulate cortex. However, we showed that there was an increase in the grey matter volume in the lenticular nucleus, caudate nucleus and a small region in the right superior parietal lobule. OCD patients also had a lower fractional anisotropy (FA) in the cingulum bundles, inferior fronto-occipital fasciculus, and superior longitudinal fasciculus, while increased FA in the left uncinate fasciculus.

Conclusions: The current findings confirm the structural abnormalities of cortico-striato-thalamic circuits in OCD.