Reduced 25-hydroxyvitamin D and risk of Alzheimer's disease and vascular dementia

Background: Vitamin D deficiency has been implicated as a risk factor for dementia in several cross-sectional studies. We tested the hypothesis that reduced plasma 25-hydroxyvitamin D (25 [OH]D) is associated with increased risk of Alzheimer's disease (AD) and vascular dementia in the general population. Methods: We measured baseline plasma 25(OH)D in 10,186 white individuals from the Danish general population. Results: During 30 years of follow-up, 418 participants developed AD and 92 developed vascular dementia. Multivariable adjusted hazard ratios for AD were 1.25 (95% confidence interval [CI], 0.95-1.64) for 25(OH)D less than 25 nmol/L vs. greater than or equal to 50 nmol/L, and 1.29 (95% CI, 1.01-1.66) for less than the 25th seasonally adjusted 25(OH)D percentile vs. more than the 50th seasonally adjusted 25(OH)D percentile. Multivariable adjusted hazard ratios for vascular dementia were 1.22(95% CI, 0.77-1.91) for 25(OH)D less than 50 nmol/L vs. greater than or equal to 50 nmol/L, and 1.22(95% CI, 0.79-1.87) for less than or equal to the 50th vs. more than the 50th seasonally adjusted 25(OH)D percentile. Last, multivariable adjusted hazard ratios for the combined end point were 1.28 (95% CI, 1.00-1.64) for 25(OH)D less than 25 nmol/L vs. greater than or equal to 50 nmol/L, and 1.27 (95% CI, 1:01-1.60) for less than the 25th vs. more than the 50th seasonally adjusted 25(OH)D. Conclusions: We observed an association of reduced plasma 25(OH)D with increased risk of the combined end point of AD and vascular dementia in this prospective cohort study of the general population. (C) 2014 The Alzheimer's Association. All rights reserved.