Does Sleep Quality Moderate the Effect of Vitamin D Intake on Risk for Dementia? (P6.185)

Objective: To determine whether vitamin D intake is associated with risk of developing dementia, and whether sleep quality moderates this relationship. Background: Both low vitamin D and poor sleep quality are independently associated with increased dementia risk. Altered circadian rhythms may disrupt the nutrient uptake process. No prior study has examined the potential moderating role of sleep on the relationship between vitamin D and dementia risk. Design/Methods: 863 older adult participants from a community-based multiethnic cohort, non-demented at baseline, completed a food frequency questionnaire and a Medical Outcomes Study Sleep Scale. Cox hazard models were conducted with tertiles of total vitamin D intake as the exposure of interest and incident all-cause dementia as the outcome, adjusting for age and sex (basic model), and additionally adjusting for race/ethnicity, level of education, and APOE E4 status (full model). Sleep quality was evaluated via a total sleep score (TSS), calculated as a sum of 12 dichotomized sleep questions. Results: During a mean follow up of 3.0 years, 147 participants developed dementia. Hazard ratios (HR) for incident dementia for highest versus lowest tertile of total vitamin D intake were 0.61 (0.40–0.93, p=0.022) in the unadjusted model, 0.60 (0.40–0.92, p=0.018) in the basic model, and 0.68 (0.44–1.03, p=0.070) in the full model. Among participants with adequate sleep quality (lowest tertile TSS), those with highest vitamin D intake had decreased risk of dementia compared to those with lowest vitamin D intake (HR 0.27, 0.098–0.75, p=0.012), in the full model. Among participants with poor sleep quality, vitamin D intake was not associated with dementia (p=0.27 and p=0.96, for the middle and highest TSS tertiles, respectively), in the full models. Conclusions: Low vitamin D intake is associated with increased risk of dementia in individuals with adequate sleep quality, but not in individuals with poor sleep quality. Study Supported by: NINDS T32 NS07153, P01AG007232, R01AG037212, RF1AG054023, AG042483 Disclosure: Dr. Zhao has nothing to disclose. Dr. Tsapanou has nothing to disclose. Dr. Manly has nothing to disclose. Dr. Schupf has nothing to disclose. Dr. Brickman has nothing to disclose. Dr. Gu has nothing to disclose.