Higher vitamin D dietary intake is associated with lower risk of alzheimer's disease: a 7-year follow-up.

BACKGROUND: Hypovitaminosis D is associated with cognitive decline among older adults. The relationship between vitamin D intakes and cognitive decline is not well understood. Our objective was to determine whether the dietary intake of vitamin D was an independent predictor of the onset of dementia within 7 years among women aged 75 years and older.
METHODS: Four hundred and ninety-eight community-dwelling women (mean, 79.8 ± 3.8 years) free of vitamin D supplements from the EPIDemiology of OSteoporosis Toulouse cohort study were divided into three groups according to the onset of dementia within 7 years (ie, no dementia, Alzheimer's disease [AD], or other dementias). Baseline vitamin D dietary intakes were estimated from self-administered food frequency questionnaire. Age, body mass index, initial cognitive performance, education level, physical activity, sun exposure, disability, number of chronic diseases, hypertension, depression, use of psychoactive drugs, and baseline season were considered as potential confounders.
RESULTS: Women who developed AD (n = 70) had lower baseline vitamin D intakes (mean, 50.3 ± 19.3 μg/wk) than nondemented (n = 361; mean intake = 59.0 ± 29.9 μg/wk, p = .027) or those who developed other dementias (n = 67; mean intake = 63.6 ± 38.1 μg/wk, p = .010). There was no difference between other dementias and no dementia (p = .247). Baseline vitamin D dietary intakes were associated with the onset of AD (adjusted odds ratio = 0.99 [95% confidence interval = 0.98-0.99], p = .041) but not with other dementias (p = .071). Being in the highest quintile of vitamin D dietary intakes was associated with a lower risk of AD compared with the lower 4 quintiles combined (adjusted odds ratio = 0.23 [95% confidence interval = 0.08-0.67], p = .007).
CONCLUSIONS: Higher vitamin D dietary intake was associated with a lower risk of developing AD among older women.