Science

Maryam Ghahremani, Eric E. Smith, Hung-Yu Chen, Byron Creese, Zahra Goodarzi, Zahinoor Ismail

Introduction
Despite the association of vitamin D deciency with incident dementia, the role of supplementation is unclear. We prospectively explored associations between vitamin D supplementation and incident dementia in 12,388 dementia-free persons from the National Alzheimer’s Coordinating Center.

Methods
Baseline exposure to vitamin D was considered D+; no exposure prior to dementia onset was considered D−. Kaplan–Meier curves compared dementia-free survival between groups. Cox models assessed dementia incidence rates across groups, adjusted for age, sex, education, race, cognitive diagnosis, depression, and apolipoprotein E (APOE) ε4. Sensitivity analyses examined incidence rates for each vitamin D formulation. Potential interactions between exposure and model covariates were explored.

Results
Across all formulations, vitamin D exposure was associated with signicantly longer dementia-free survival and lower dementia incidence rate than no exposure (hazard ratio = 0.60, 95% condence interval: 0.55–0.65). The eect of vitamin D on incidence rate diered signicantly across the strata of sex, cognitive status, and APOE ε4 status.

Discussion
Vitamin D may be a potential agent for dementia prevention.