Abstract
INTRODUCTION: Biological evidence suggests that vitamin D might be involved in regulating mood. The relationship between 25-hydroxyvitamin D (25OHD) and the onset of depressive symptoms was examined over a 4.4-year follow-up in a sample of older adults. METHODS: This research was part of the Progetto Veneto Anziani (Pro.V.A.), an Italian population-based cohort study on a total of 1,039 women and 636 men aged 65 and older. Serum 25OHD levels were measured at baseline. Depressive symptoms were assessed with the Geriatric Depression Scale (GDS) at the baseline and during the follow-up. Analyses were adjusted for relevant confounders, including health and performance status. RESULTS: 25OHD levels correlated inversely with baseline GDS scores, but only in women. After controlling for confounders, women deficient in vitamin D (25OHD < 50 nmol/L) had higher GDS scores than those who were replete (25OHD > 75 nmol/L), with mean [SE] GDS scores: 9.57 [0.37] vs 8.31 [0.31], respectively, p = .02. In men, the relationship between 25OHD levels and baseline GDS scores was no longer significant after controlling for covariates. Adjusted hazard ratios and 95% confidence intervals for incident depression in participants who were vitamin D deficient vs replete were not statistically significant (hazard ratio: 0.74, 95% confidence interval [0.47-1.16] in women; hazard ratio: 0.96 95% confidence interval [0.45-2.06] in men). CONCLUSION: Although an independent inverse association between 25OHD levels and GDS scores emerged for women on cross-sectional analysis, vitamin D deficiency showed no direct effect on the onset of late-life depressive symptoms in our prospectively studied population. Further studies are warranted to clarify the potential influence of vitamin D on psychological health.