The Effects and Neural Mechanisms of Vitamin D and Iron-Immune Homeostasis on Inhibitory Control in Obsessive-Compulsive Disorder

This study is a randomized, open-labled, no-treatment-controlled clinical trial designed to investigate the effects of vitamin D and iron-immune homeostasis on inhibitory control and the underlying neural mechanisms in patients with obsessive-compulsive disorder (OCD). Participants will be patients with OCD who meet the study eligibility criteria.

The study's primary aim is to compare changes in glutamate and related metabolite concentrations within the anterior cingulate-thalamic circuit, inhibitory control performance, peripheral immune markers, and clinical symptoms before and after treatment with calcitriol and iron polysaccharide complex. The study will also investigate the neural-circuit mechanisms underlying inhibitory control deficits in patients with OCD and their changes following the interventions. These objectives will be addressed using resting-state Magnetic Resonance Spectroscopy(MRS), inhibitory control tasks, peripheral blood immune-marker measurements, and clinical symptom assessments.

The primary hypothesis is that inhibitory control deficits in patients with OCD are associated with dysregulated glutamatergic metabolism in the anterior cingulate-thalamic circuit. Vitamin D and iron supplementation are hypothesized to promote the balance of glutamate and related metabolites within this circuit, regulate immune homeostasis, and improve inhibitory control deficits in patients with OCD.