Structural and functional deficits and couplings in severe and moderate OCD

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Obsessive-compulsive disorder (OCD) pathophysiology is complex, with observed gray matter volume and functional connection changes.
• Previous studies often lack detailed subgroup analysis based on symptom severity, potentially leading to oversimplified conclusions.
• Multimodal neuroimaging studies examining structural-functional coupling in OCD are relatively rare.

Purpose of the Study:

• To investigate gray matter volume (GMV) and functional network abnormalities in OCD patients categorized by symptom severity (severe-OCD, moderate-OCD) compared to healthy controls (HCs).
• To explore the relationship between structural deficits and functional connectivity alterations.
• To identify potential correlations between neuroimaging findings and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores.

Main Methods:

• Voxel-based morphometry (VBM) was employed to detect GMV differences among severe-OCD, moderate-OCD, and HC groups.
• Resting-state functional connectivity (rs-FC) analysis was performed using GMV differences as masks.
• Correlation and subgroup analyses were conducted to examine structural deficits and their relationship with symptom severity.

Main Results:

• Both severe-OCD and moderate-OCD groups showed increased GMV in the anterior cingulate cortex (ACC), left precuneus (L-Pre), paracentral lobule (PCL), and occipital regions (L-IOG, R-SOG, MOG).
• Increased functional connections were observed between the precuneus (Pre) and angular gyrus (AG)/inferior parietal lobule (IPL), and within occipital-cerebellar networks.
• Decreased GMV in the left caudate was negatively correlated with compulsion and total Y-BOCS scores in the moderate-OCD group.

Conclusions:

• Altered GMV in the ACC, L-Pre, PCL, and occipital regions, along with disrupted functional connectivity in MOG-cerebellum and Pre-AG/IPL networks, are characteristic of OCD.
• Subgroup analysis highlights a negative association between GMV changes and symptom severity (Y-BOCS scores).
• These findings provide evidence for the involvement of structural and functional deficits within cortical-subcortical circuitry in OCD's neurobiological basis.