Serum 25-Hydroxyvitamin D Levels and Depression in Older Adults: A Dose-Response Meta-Analysis of Prospective Cohort Studies

Objective: The association between serum vitamin D and risk of depression in older adults is controversial. We performed a dose-response meta-analysis of prospective cohort studies to examine the association between serum 25-hydroxy-vitamin D [25(OH)D] concentrations and the risk of depression in older population. Methods: Studies published before February 2018 in the PubMed, Cochrane Library, Web of Science, PsycINFO, and EMBASE databases were systematically searched. Prospective cohort studies that examined the association between serum 25(OH) D levels and the risk of depression in older adults were included. A random-effects model was used to calculate the pooled hazard ratio and the corresponding 95% confidence intervals. A nonlinear dose-response association was examined using restricted cubic spline functions. Results: Six prospective studies covering 16,287 older adults with 1,157 cases of depression were included and analyzed. The pooled hazard ratio of depression for per 10-ng/mL increment in serum 25(OH)D was 0.88 (95% confidence intervals: 0.78-0.99, I-2 = 79.0%, p < 0.001 for heterogeneity). A linear dose-response association between serum 25(OH) D concentrations and incident depression was observed (p = 0.96 for nonlinearity). Conclusion: Serum25(OH)D concentration is negatively associated with the risk of depression in older adults. This meta-analysis suggests that increasing 25(OH)D levels may be a useful approach to reduce the risk of depression in older adults and highlights the need for further large-scale clinical studies.