Decreased gray matter volume and dynamic functional alterations in medicine-free obsessive-compulsive disorder

BackgroundPrevious studies discovered the presence of abnormal structures and functions in the brain regions of patients with obsessive-compulsive disorder (OCD). Nevertheless, whether structural changes in brain regions are coupled with alterations in dynamic functional connectivity (dFC) at rest in medicine-free patients with OCD remains vague.MethodsThree-dimensional T-1-weighed magnetic resonance imaging (MRI) and resting-state functional MRI were performed on 50 medicine-free OCD and 50 healthy controls (HCs). Firstly, the differences in gray matter volume (GMV) between OCD and HCs were compared. Then, brain regions with aberrant GMV were used as seeds for dFC analysis. The relationship of altered GMV and dFC with clinical parameters in OCD was explored using partial correlation analysis. Finally, support vector machine was applied to examine whether altered multimodal imaging data might be adopted to distinguish OCD from HCs.ResultsOur findings indicated that GMV in the left superior temporal gyrus (STG) and right supplementary motor area (SMA) was reduced in OCD, and the dFC between the left STG and the left cerebellum Crus I and left thalamus, and between the right SMA and right dorsolateral prefrontal cortex (DLPFC) and left precuneus was decreased at rest in OCD. The brain regions both with altered GMV and dFC values could discriminate OCD from HCs with the accuracy of 0.85, sensitivity of 0.90 and specificity of 0.80.ConclusionThe decreased gray matter structure coupling with dynamic function in the left STG and right SMA at rest may be crucial in the pathophysiology of OCD.

Automated summary

Previous studies have found abnormal structures and functions in the brains of OCD patients. However, it is still unclear whether structural changes in the brain regions are related to alterations in dynamic functional connectivity in medicine-free OCD patients at rest. This study compared the gray matter volume differences between 50 medicine-free OCD patients and 50 healthy controls using MRI, and found reduced gray matter volume in the left superior temporal gyrus and right supplementary motor area in OCD patients, along with decreased dynamic functional connectivity in these brain regions. Finally, the study showed that the altered multimodal imaging data could accurately distinguish OCD patients from healthy controls with a high sensitivity and specificity.