Effect of vitamin D supplementation on depression in older Australian adults

ObjectivesTo investigate whether vitamin D supplementation reduces depressive symptoms and incidence of antidepressant use. MethodsWe used data from the D-Health Trial (N = 21,315), a randomized double-blind placebo-controlled trial of monthly vitamin D-3 for the prevention of all-cause mortality. Participants were Australians aged 60-84 years. Participants completed the Patient Health Questionnaire (PHQ-9) at 1, 2 and 5 years after randomization to measure depressive symptoms; national prescribing records were used to capture antidepressant use. We used mixed models and survival models. ResultsAnalyses of PHQ-9 scores included 20,487 participants (mean age 69 center dot 3 years, 46% women); the mean difference (MD) in PHQ-9 score (vitamin D vs. placebo) was 0 center dot 02 (95% CI -0 center dot 06, 0 center dot 11). There was negligible difference in the prevalence of clinically relevant depression (PHQ-9 score >= 10) (odds ratio 0 center dot 99; 95% CI 0 center dot 90, 1 center dot 08). We included 16,670 participants in the analyses of incident antidepressant use (mean age 69 center dot 4 years, 43% women). Incidence of antidepressant use was similar between the groups (hazard ratio [HR] 1 center dot 04; 95% CI 0 center dot 96, 1 center dot 12). In subgroup analyses, vitamin D improved PHQ-9 scores in those taking antidepressants at baseline (MD -0 center dot 25; 95% CI -0 center dot 49, -0 center dot 01; p-interaction = 0 center dot 02). It decreased risk of antidepressant use in participants with predicted 25(OH)D concentration <50 nmol/L (HR 0 center dot 88; 95% CI 0 center dot 75, 1 center dot 02; p-interaction = 0 center dot 01) and increased risk in those with predicted 25(OH)D >= 50 nmol/L (HR 1 center dot 10; 95% CI 1 center dot 01, 1 center dot 20). ConclusionMonthly supplementation with high-dose vitamin D-3 was not of benefit for measures of depression overall, but there was some evidence of benefit in subgroup analyses. Clinical Trial RegistrationThe trial is registered on the Australian New Zealand Clinical Trials Registry: ACTRN12613000743763. .