The “sunshine vitamin” in obsessive-compulsive disorder: a systematic review and meta-analytical evaluation of its association with disease etio-pathophysiology

Introduction Decrements in the circulating levels of vitamin D (vitD) are frequently associated with psychiatric conditions, often correlating with disorder severity. However, whether hypovitaminosis D is linked to incidence and symptom severity of obsessive-compulsive disorder (OCD) remains obscure. The purpose of this systematic review and comprehensive meta-analytical assessment was to evaluate the relationship between categorical and numerical parameters of endogenous vitD status and OCD etio-pathophysiology. Methods Using a systematic scheme, we retrieved clinical data from peer-reviewed journals indexed in scholarly online databases (PubMed, Google Scholar, and EMBASE) in accordance with the PRISMA guidelines. First, we tested for the differences in vitD levels in OCD cases, compared to controls. Following this, the association between vitD deficiency (VDD) and OCD was examined using categorical data. Finally, we assessed correlation between vitD levels and symptom severity in OCD cases. Results Compared to the controls, circulating vitD levels were significantly decreased in OCD cases (standardized mean difference = −0.669 [95% CI: −0.943, −0.394]). Interestingly, VDD was associated with significantly enhanced odds of being diagnosed with OCD (odds ratio = 4.059 [95% CI: 1.984, 8.314]). Further, vitD levels correlated negatively with the subjects’ total (pooled r = −0.361 [95% CI: −0.566, −0.157]), obsessive (pooled r = −0.383 [95% CI: −0.570, −0.196]), and compulsive (pooled r = −0.257 [95% CI: −0.456, −0.058]) symptoms. Discussion Our results indicate a significant relationship between endogenous vitD levels and OCD etio-pathology, with the diminished circulating levels of vitD correlating with OCD severity. While a causal relationship could not be established, the findings provide a research platform for future interventional trials to evaluate the effects of exogenous vitD supplementation in the management of OCD cases.