Vitamin D Status Predicts Rates of Cognitive Decline in a Multi‐Ethnic Cohort of Older Adults

Abstract

Vitamin D (VitD) deficiency is associated with cognitive decline and risk of dementia. We assessed associations between VitD and cognitive decline in an ethnically diverse cohort of older adults (N=382; age 76±7y; 41% White, 26% Hispanic, 29% African‐American, 4% other). Serum 25‐hydroxyvitamin D (25OHD) was measured by immunoassay. VitD status was defined as deficiency, <12 ng/ml; insufficiency, 12‐20 ng/ml; adequacy, >20 ng/ml. Cognitive function was assessed at baseline and yearly using the Spanish English Neuropsychological Assessment Scales (mean follow‐up: 4.8±2.5y). Baseline diagnoses were dementia, 17%; mild cognitive impairment (MCI), 33%; cognitively normal, 50%. Mean 25OHD was 19.2±11.7 ng/ml; 26% were deficient, 35% were insufficient. 25OHD was lower in demented subjects compared with MCI and cognitively normal (16.2±9.4 vs 20.0±10.3 and 19.7±13.1 ng/ml; p=0.07). Controlling for age, sex, education, ethnicity, BMI, season, vascular risk, and apoE4, rates of cognitive decline were greater in VitD deficient and insufficient subjects compared with those with adequate VitD status for episodic memory and executive function (p<0.03). Associations of VitD with declines in semantic memory and visuospatial ability were not statistically significant. Exclusion of demented subjects did not affect the associations of VitD with cognitive decline. Low VitD status is associated with accelerated rates of decline in domains of cognitive function in ethnically diverse older adults. It remains to be determined if VitD supplements slow cognitive decline. NIH AG010129‐21