Cognition and Vitamin D in Older African‐American Women– Physical performance and Osteoporosis prevention with vitamin D in older African Americans Trial and Dementia

Abstract

OBJECTIVES To examine the effect of 25‐hydroxyvitamin D (25(OH)D) levels recommended by Endocrine Society guidelines (>30 ng/mL) on cognition in healthy older African‐American women over 3 years. DESIGN Randomized, double‐blind, placebo‐controlled clinical trial. SETTING Bone Mineral Research Center at New York University Winthrop Hospital. PARTICIPANTS Healthy postmenopausal African American women aged 65 and older (N=260; mean age 68.2 ± 4.9; 46% college education or higher). INTERVENTION Half of the women were randomized to receive vitamin D (adjusted to achieve a serum level > 30 ng/mL) with calcium (diet and supplement total of 1,200 mg), and half were randomized to receive placebo with calcium (1,200 mg). MEASUREMENTS Cognitive assessments every 6 months using the Mini‐Mental State Examination (MMSE) to detect cognitive decline. Mean MMSE scores were calculated over time for both groups. Those with MMSE scores less than 21 at baseline were excluded. RESULTS The average dose of vitamin D3 was 3,490 ± 1,465 IU per day, and average serum 25(OH)D at 3 years was 46.8 ± 1.2 ng/mL in the active group and 20.7 ± 1.1 ng/mL in the placebo group. Serum 25(OH)D concentration was maintained at greater than 30 ng/mL in 90% of the active group. Over the 3‐year period, MMSE scores increased in both groups (p < .001), although change over time was not significantly different between the groups. No adverse events associated with vitamin D were observed. CONCLUSION There was no difference in cognition over time between older African‐American women with serum concentrations of 25(OH)D of 30 ng/mL and greater than those taking placebo. There is no evidence to support vitamin D intake greater than the recommended daily allowance in this population for preventing cognitive decline. J Am Geriatr Soc 67:81–86, 2019.

Efficacy of Vitamins on Cognitive Function of Non-Demented People: A Systematic Review and Meta-Analysis

“…All included trials used only vitamin D3 with its dosage varied from 400 to 3600 IU daily. As for sex distribution, two studies had only females [56,57]. One study included individuals younger than 60 years old [58].…”

“…One study evaluated those with MCI at baseline only [59], and one study included participants with cerebrovascular disease [58]. Concerning the baseline level of vitamin D, three studies recruited those with a decreased level of serum 25(OH)D concentration, with their cut-points ranging from 16.8 to 26 ng/mL [54,56,58].…”

“…A detailed description of the cognitive tests is presented in the Supplementary Materials (Table S3). We found that the most frequently used neuropsychological test for each cognitive domain was the mini-mental state examination (MMSE) for global cognition [22,24,25,32,33,35,37,39,48,51,54,56,57], delayed recall from California Verbal Learning Test (CVLT) for episodic memory [25,33,44,57], verbal fluency for executive function [24,28,32,35,[37][38][39]41,44,47,49,50,53,57], digit symbol substitution/modality/coding test for processing speed [29,34,36,37,39,41,42,44,58,59], digit span backward for attention [24,34,38,39,42,…”

“…After exclusion of six studies that included pre-existing conditions such as cerebrovascular disease and diabetes mellitus [24,[27][28][29]31,58], overall findings did not change except that the effect of B vitamins on global cognition in studies from Asia and the Middle East became significant (SMD −0.76, 95% CI −0.98 to −0.53, n = 320) with an improved statistical heterogeneity (tau 2 = 0.00 and I 2 = 0%). Exclusion of trials that recruited participants with vitamin B12 deficiency, elevated homocysteine, or vitamin D deficiency [23,27,32,35,36,38,39,41,44,54,56,58] also resulted in inconsiderable changes, except that the effect of 12 or more months of B vitamin intake on global cognition became nonsignificant (SMD −0.11, 95% CI −0.27 to 0.05, n = 2851).…”

Vitamin D deficiency as a risk factor for dementia and Alzheimer’s disease: an updated meta-analysis

“…Organisms primarily obtain vitamin D through food intake and skin synthesis. A published clinical study estimated that there are 1 billion people worldwide with vitamin D deficiency due to a lack of exposure to sunlight [7]. In addition, people residing in regions with less sunlight need to consume more foods rich in vitamin D [8].…”