Dose Ranging Effects of Vitamin D3 on the Geriatric Depression Score: A Clinical Trial

Depression is a common problem affecting millions, usually treated with selective serotonin uptake inhibitors. Interest in vitamin D as a co-therapy was stimulated by some association studies that correlated depression with low serum 25OHD levels. There are few longitudinal studies of vitamin D and depression and most are single doses of vitamin D. In this study we examined the effect of one-year treatment with several doses of vitamin D on the Geriatric depression score (GDS) in older Caucasian and African American women. The clinical trial was a study of seven daily oral doses of vitamin D (400-4800IU/d) in Black and White older women. The trial was a double blind, randomized and placebo controlled lasting 12-months. The main inclusion criterion was serum 25 hydroxyvitamin D (25OHD)≤20ng/mL (50nmol/L). Calcium supplements were given to maintain calcium intake 1000mg/day in young people and 1200-1400mg/day in older women. Data on Geriatric depression (GDS) was collected using the validated long form at baseline and 12-months. The change in serum 25OHD was the primary outcome and GDS was one of the secondary outcomes. Adjustments were made for relevant covariates. Analysis of vitamin D effect was by dose low, medium and high compared to placebo or by quintiles. Serum 25OHD increased as a quadratic curve function to a mean of 46ng/mL (115nmol/L) in white women and 49ng/mL (122.5nmol/L) in black women on the highest dose of 4800 IU. In older women mean GDS scores changed from 3.8 (SD±4.2) at baseline to 3.6 (SD±4.1) at 12 months in whites and from 3.0 (SD±3.7) to 3.02 (SD±4.2) in Blacks. (p=0.790 in whites; p=0.958 in blacks). After 12-months there was no effect of dose on change in GDS score in women treated with different doses of vitamin D (p=0.507 in whites and p=0.340 in blacks). When both Caucasians and African Americans were divided into 3 dose groups, low (400-800 IU), medium (1600-3200 IU) and high (4000-4800 IU) doses, the change in score was 0.8 on low dose, -0.30 on medium dose and -0.31 on high dose compared to 0.11 on placebo (p=0.546). In summary, there was no improvement in GDS scores in Caucasians or African Americans on either increasing doses of vitamin D or quintiles of achieved response in serum 25OHD. The changes were small and not significant perhaps because of the relatively lower numbers of depressed women in the groups. Further studies should recruit larger numbers, 3 dose groups covering a serum25OHD range of 20-60ng/mL and more subjects with clinical depression in order to fully address the question of vitamin D effects on depression.