P3-317: vitamin d insufficiency predicts incident cognitive impairment in an elderly multiethnic adc cohort

We previously reported that vitamin D insufficiency is associated with faster decline in episodic memory and executive function (Miller et al 2015 JAMA Neurology). In the present study, we investigated if vitamin D insufficiency is also associated with increased incidence of cognitive impairment (i.e. diagnostic change from normal cognition to MCI or dementia) or an increased conversion rate from mild cognitive impairment (MCI) to dementia. ± 6.9 years in this multi-ethnic cohort (included 95 African Americans, 76 Hispanics). We used Cox proportional hazard models, both unadjusted and adjusted for age, ethnicity, sex, education, BMI, season of blood draw, and apolipoprotein E4 carrier, to compare conversion rates in participants with vitamin D insufficiency (25-OHD levels ≤ 20 ng/ml) versus normal vitamin D levels. Preliminary results showed that vitamin D insufficiency was associated with an increased rate of conversion from normal cognition to MCI or dementia (unadjusted HR= 1.87, [95% CI: 1.11-3.16]; adjusted model HR= 3.27, [95% CI: 1.72-6.20]) as was older age (HR= 1.13, [95% CI: 1.08-1.19]). However, vitamin D insufficiency was not associated with a significantly increased risk for conversion from MCI to dementia (adjusted model HR= 1.39, [95% CI: 0.74-2.62]). Vitamin D insufficiency conferred an increased risk of developing cognitive impairment among those with normal cognition in our diverse elderly cohort. This is consistent with a growing literature which suggests that vitamin D is important for maintaining normal cognitive function. However, among those with MCI, vitamin D status did not predict conversion to dementia. Prospective randomized trials are needed to test if vitamin D supplementation can reduce dementia risk or cognitive decline in diverse elderly populations with vitamin D insufficiency.