Abnormal functional connectivity density in patients with obsessive-compulsive disorder.

OBJECTIVE

This study investigated abnormal short- and long-range functional connectivity density (FCD) and resting-state functional connectivity (rsFC) within and outside the cortico-striatal-thalamic (CST) loop in patients with obsessive-compulsive disorder (OCD).

METHODS

Ninety-two patients with OCD and 75 healthy controls underwent multimodal MRI. Clinical assessments included the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Beck Anxiety Inventory, and Beck Depression Inventory. Voxel-based FCD analysis explored local and distant nodal changes, followed by seed-based rsFC analysis and correlation with clinical variables.

RESULTS

Compared with healthy controls, patients with OCD showed decreased short-range FCD in the bilateral postcentral gyrus, left superior temporal gyrus, and right insula, but increased short-range FCD in the left caudate nucleus. Long-range FCD increased in the right orbitofrontal gyrus and left middle frontal gyrus. Seed-based analysis revealed enhanced rsFC between the right orbitofrontal gyrus and right calcarine fissure and surrounding cortex, and between the left middle frontal gyrus and right anterior cingulate and paracingulate gyri, as well as the right paracentral lobule. Left caudate FCD values negatively correlated with Y-BOCS scores, while left middle frontal gyrus FCD values positively correlated with illness duration.

CONCLUSION

Patients with OCD exhibit widespread connectivity abnormalities in multiple brain regions within and beyond the classic CST loop, involving sensorimotor networks, emotion-cognitive regulation, executive control, error monitoring, and visual processing systems. These findings suggest that OCD pathophysiology extends beyond the traditional CST loop, providing new insights into the neural mechanisms underlying this disorder.