Association of vitamin D levels with incident depression among a general cardiovascular population

BackgroundDepression is associated with cardiovascular (CV) disease, and it has been hypothesized that vitamin (vit)D deficiency may be associated with depression and a contributing factor to excess CV events. Therefore, we evaluated whether there is an association between vitD and incident depression among a CV population.MethodsPatients (N = 7,358) ≥50 years of age, with a CV diagnosis (coronary artery disease, myocardial infarction, congestive heart failure, cerebrovascular accident, transient ischemic accident, atrial fibrillation, or peripheral vascular disease), no prior depression diagnosis, and a measured vitD level were studied. Vitamin D (ng/mL) was stratified into 4 categories: >50 (optimal [O] n = 367), 31 to 50 (normal [N] n = 2,264), 16 to 30 (low [L] n = 3,402), and ≥15 (very low [VL] n = 1,325). Depression was defined by International Classification of Diseases, Ninth Edition, codes: 296.2 to 296.36, 311. VitD categories were evaluated by Cox hazard regression with adjustment by standard CV risk factors.ResultsAge averaged 73.1 ± 10.2 years, and 58.8% were female. When compared to O, VL, L, and N were associated with depression (adjusted: VL, hazard ratio [HR] 2.70 [1.35-5.40], P = .005; L, HR 2.15 [1.10-4.21], P = .03; N, HR 1.95 [0.99-3.87], P = .06). This association remained even after adjustment by parathyroid hormone levels. Parathyroid hormone was significantly associated with depression, however, became nonsignificant after adjustment by vitD. Winter (December-February) enhanced this association. Significant associations remained when stratifications were made by age (<65, ≥65), sex, and diabetes, although the associations among those age ≥65 and male sex were enhanced.ConclusionAmong a CV population ≥50 years with no history of depression, vitD levels were shown to be associated with incident depression after vitD draw. This study strengthens the hypothesis of the association between vitD and depression.