Disorder-specific cerebellar-cerebral functional connectivity in OCD relative to GAD: A seed-based fMRI analysis

In recent years, neuroimaging studies implicate cerebellum in the pathophysiology of obsessive-compulsive disorder (OCD) and generalized anxiety disorder (GAD).

Given the high comorbidity of OCD with anxiety, and the difficulty in excluding confounding factors of comorbid anxiety in previous studies' sample selection, we conducted cerebellar seed-based functional connectivity (FC) analysis in 105 participants (39 OCD, 35 GAD, 31 HCs).

Compared to HCs, OCD patients exhibited increased FC in the left Crus I_DMN - anterior cingulate cortex (ACC). Compared to GAD group, OCD patients exhibited reduced FC between the cerebellum and the sensorimotor network, as well as the right medial superior frontal gyrus. Negative correlations were observed between Y-BOCS compulsion scores and FC, specifically between the left Crus I_ECN1 and the right middle temporal pole, as well as between the right Lobule V_Mot and the right precentral gyrus. As for the GAD group, compared to HCs, Patients with GAD primarily exhibited abnormalities in FC between the cerebellum and the executive control network (ECN), sensorimotor networks, and limbic regions. Elevated FC in the left Crus I_DMN - orbitofrontal cortex (OFC), as well as in the right Crus I_ECN1 - right medial superior frontal gyrus, was significantly negatively correlated with HAMA scores.

Our findings demonstrate that OCD exhibited widespread abnormalities in cerebro-cerebellar FC, particularly involving sensorimotor networks and the medial frontal cortex. This further supported cerebellar role in OCD pathophysiology.