Altered gray matter and resting-state functional connectivity in obsessive-compulsive disorders predominantly with obsessional thoughts

Abstract

Objective To explore the changes of brain gray matter volume and resting-state functional connectivity in obsessive-compulsive disorders (OCD) predominantly with obsessional thoughts. Methods Twenty OCD patients predominantly with obsessional thoughts, 20 OCD patients with mixed type, and 20 age-, sex- and education-matched healthy controls were enrolled. MRI scan was done for each participant. Gray matter volume was investigated by voxel-based morphometry (VBM) analysis, the brain regions of abnormal gray matter volume were used as the interested regions to carry out the whole brain function connectivity analysis at resting-state. Spearman correlation analysis was used to analysis the relationship between the whole brain functional connectivity and clinical symptoms in OCD. Results Compared with the healthy group, OCD patients predominantly with obsessional thoughts showed significantly decreased gray matter volume in right pallidum (0.17±0.02 vs.0.10±0.01) , significantly increased gray matter volumes in right lingual (0.39±0.04 vs. 0.47±0.07) and right parietal lobe(0.22±0.02 vs. 0.30±0.05; t=-25.37, 5.03, 7.79; GRF corrected, P<0.05) . OCD patients with mixed type showed significantly decreased gray matter volume in left pallidum, significantly increased gray matter volumes in right lingual and left inferior temporal gyrus (t=-24.87, 6.17, 11.37; GRF corrected, all P<0.05) . OCD patients predominantly with obsessional thoughts showed decreased functional connectivity of right pallidum inside, right pallidum with right cerebellum, and left pallidum, increased functional connectivity with the left supplementary motor area (t=-7.44, -4.03, -4.30, 3.93, t=3.93, GRF corrected, all P<0.05) . Significant positive correlation was found between functional connectivity of the right pallidum with right cerebellum and disease course in OCD patients predominantly with obsessional thoughts (r=0.488, P=0.029). Conclusions OCD patients predominantly with obsessional thoughts in brain gray matter volume and resting-state functional connectivity is possibly abnormal, the abnormalities may be within the cortico-striatal-thalamic-cortical circuit, and cerebellum also be involved in the pathophysiological mechanism of obsessional thoughts. Key words: Obsessive-compulsive disorder; Magnetic resonance imaging; Voxel-based morphometry; Gray matter; Functional connectivity