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

Overview

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.

Previous studies have provided evidence suggesting that vitamin D and iron supplementation may have beneficial effects in the treatment of obsessive-compulsive disorder (OCD); however, the underlying mechanisms remain unclear. Our preliminary findings indicate that inhibitory control deficits in OCD are associated with abnormalities in glutamate metabolism within the anterior cingulate-thalamic circuit. Further research suggests that disruptions in iron- and vitamin D-related immune homeostasis may affect glutamate metabolism and function. Baseline data will be collected upon enrollment, including resting-state Magnetic Resonance Spectroscopy (MRS) data, performance on inhibitory control tasks, peripheral blood immune markers, and clinical symptom assessments. The key research questions to be addressed are: 1. Whether inhibitory control performance differs before and after treatment with calcitriol and iron polysaccharide complex; 2. Whether resting-state glutamate levels within the anterior cingulate-thalamic circuit differ before and after treatment with calcitriol and iron polysaccharide complex; 3. Whether glutamate and related metabolite levels within the anterior cingulate-thalamic circuit are associated with inhibitory control performance, peripheral blood immune markers, and clinical symptoms before and after treatment with calcitriol and iron polysaccharide complex. After eligibility has been confirmed according to the inclusion and exclusion criteria and written informed consent has been obtained, all participants will complete a demographic and clinical information questionnaire, clinical symptom assessments, peripheral blood tests, and cognitive function tests. Participants will subsequently undergo magnetic resonance examination, including resting-state MRS performed under quiet resting conditions. The intervention will last for three months. Follow-up assessments will be conducted at 1, 3, 6, and 12 months after completion of the intervention.