Abnormal voxel-mirrored homotopic connectivity in first-episode, drug-naïve patients with obsessive-compulsive disorder.

Prior studies suggest that obsessive-compulsive disorder (OCD) can cause both anatomical and functional variations in the brain, but to date, altered functional synchronization between two functional hemispheres remains unclear in OCD patients. Voxel-mirrored homotopic connectivity (VMHC) is defined as the temporal correlation of spontaneous low-frequency blood oxygenation level-dependent signal fluctuations across mirror regions of hemisphere revealing the homotopic connectivity between each voxel in one hemisphere and its mirrored counterpart in the contralateral hemisphere. To investigate the alterations of brain regional function and VMHC in patients with OCD, the current study enrolled 103 OCD patients and 118 healthy controls, undergoing resting-state functional magnetic resonance imaging. Compared to healthy controls (HCs), patients had decreased VMHC in bilateral cerebellum, lingual and fusiform gyrus; bilateral paracentral lobule, pre and postcentral gyrus; and bilateral superior and middle temporal gyrus, putamen and bilateral precuneus without global signal regression. And we found mostly similar results after regressing global signals; apart from the regions mentioned above, decreased in bilateral cuneus and calcarine was also showed. Furthermore, the mean VMHC values of the left cerebellum were negatively correlated with the obsession scores (ρ = -.204, π = .039). The decreased values in right fusiform and putamen were negatively correlated with duration of disease (ρ = -.205, π = .038; ρ = -.196, π = .047). We confirmed a significant VMHC reduction in OCD patients in broad areas. Our findings suggest that the patients tend to disconnect information exchange across hemispheres.