The association between low vitamin D and depressive disorders

It has been hypothesized that hypovitaminosis D is associated with depression but epidemiological evidence is limited. We investigated the association between depressive disorders and related clinical characteristics with blood concentrations of 25-hydroxyvitamin D [25(OH) D] in a large cohort. The sample consisted of participants (aged 18-65 years) from the Netherlands Study of Depression and Anxiety (NESDA) with a current (N = 1102) or remitted (N = 790) depressive disorder (major depressive disorder, dysthymia) defined according to DSM-IV criteria, and healthy controls (N = 494). Serum levels of 25(OH) D measured and analyzed in multivariate analyses adjusting for sociodemographics, sunlight, urbanization, lifestyle and health. Of the sample, 33.6% had deficient or insufficient serum 25(OH) D (<50 nmol l(-1)). As compared with controls, lower 25(OH) D levels were found in participants with current depression (P = 0.001, Cohen's d = 0.21), particularly in those with the most severe symptoms (P = 0.001, Cohen's d = 0.44). In currently depressed persons, 25(OH) D was inversely associated with symptom severity (beta = -0.19, s.e. -0.07, P = 0.003) suggesting a dose-response gradient, and with risk (relative risk = 0.90, 95% confidence interval = 0.82-0.99, P = 0.03) of having a depressive disorders at 2-year follow-up. This large cohort study indicates that low levels of 25(OH) D were associated to the presence and severity of depressive disorder suggesting that hypovitaminosis D may represent an underlying biological vulnerability for depression. Future studies should elucidate whether-the highly prevalent-hypovitaminosis D could be cost-effectively treated as part of preventive or treatment interventions for depression.