Vitamin D level predicts all-cause dementia

BACKGROUND: Vitamin D deficiency is common in Western societies and has been implicated in a number of health conditions including late-life dementia. OBJECTIVE: To assess whether vitamin D level is associated with all-cause dementia in late life. METHODS: This was a retrospective case control study using the electronic medical record of an urban medical center to obtain information on age, sex, body mass index, 25-hydroxy vitamin D (25-(OH)D) values, and presence of dementia diagnosis in patients 65 to 90 years old. We classified patients to quartiles according to vitamin D values and performed logistic regression analysis to determine associations between vitamin D quartiles and incidence of dementia diagnosis. RESULTS: Rates of all-cause dementia decreased with increasing levels of 25-(OH)D independent of age, sex, and BMI, factors that also predicted dementia. Vitamin D levels above 38 ng/mL were associated with the lowest rate of all-cause dementia. CONCLUSIONS: We observed dose-dependent, inverse associations of 25-hydroxy vitamin D levels with all-cause, late life dementia independent of age, sex, and BMI. There may be greater protection for supra-sufficient levels, a notion that warrants evaluation in controlled trials.