Vitamin D is associated with cognitive function in elders receiving home health services

Authors: BUELL, JENNIFER - TUFTS UNIVERSITY; SCOTT, TAMMY - TUFTS MEDICAL CTR, MA; Dawson-Hughes, Bess; Dallal, Gerald; Rosenberg, Irwin; FOLSTEIN, MARSHAL - TUFTS UNIVERSITY; Tucker, Katherine

Submitted to: Journal of Gerontology Medical Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2008
Publication Date: 4/17/2009
Citation: Buell, J.S., Scott, T.M., Dawson-Hughes, B., Dallal, G., Rosenberg, I., Folstein, M., Tucker, K. 2009. Vitamin D is associated with cognitive function in elders receiving home health services. Journal of Gerontology Medical Science. 64A(8):888-895.

Interpretive Summary: New research suggests that vitamin D has beneficial effects on muscle function, cardiovascular health, diabetes, and cancer prevention. More recently, clinical studies have suggested a potential beneficial role of vitamin D for cognitive function. A growing body of evidence suggests that the active form of vitamin D is involved in developing and adult brain function. Homebound elders bear a disproportionate burden of disease, are more likely to have cognitive impairment and are particularly at risk for vitamin D insufficiency because of sunlight deprivation, inadequate nutriture, age-related dermatological changes, and impairments in renal function. This study was designed to evaluate associations between vitamin D concentration and cognitive function, specifically aspects of executive function, memory, and attention/processing speed, in an urban dwelling, racially diverse homebound elderly population in Boston, MA. More than 65 % of participants had suboptimal vitamin D concentrations and approximately 18 % were deficient in vitamin D. Higher vitamin D concentration was associated with better performance on several cognitive tests, particularly with measures of executive function in this elderly population. Our results show that vitamin D is positively associated with cognitive performance and underscores that insufficiency is a significant problem in home-dwelling elders. Further study to explore the physical and neuroprotective effects of vitamin D may provide important clues to approaches to maintain independence for community dwelling elderly individuals.

Technical Abstract: Vitamin D status has recently been associated with neurological disorders, but little research has evaluated vitamin D and cognitive function. We conducted a cross-sectional investigation of 25-hydroxyvitamin D (25OHD) and cognitive function in 377 black and 703 non-black (Caucasian, Hispanic, Asian) homebound elders (65–99 y) from 2001-06. More than 65 % of elders had suboptimal 25OHD concentrations (<20 ng/mL or <50 nmol/l). Approximately 18 % were deficient in 25OHD (<10 ng/mL or <25 nmol/l). Only 7.6 % had vitamin D concentrations >30 ng/mL (75nmol/l). After adjusting for age, sex, race, BMI, education, center, kidney function, seasonality, and alcohol use, 25OHD was associated with better performance on trails A (beta= -0.60; P<0.01), trails B (beta= -0.83; P<0.01), digit symbol (beta= 0.20; P<0.001), matrix reasoning (beta= 0.04; P<0.02), and block design (beta= 0.08; P<0.03). Associations remained after adjustment for homocysteine, apoE4 allele, plasma B vitamins, and multivitamin use (y/n). Vitamin D concentrations >20 ng/mL was associated with better mean scores on tests of executive function, including trails A (80.5 vs 96; P<0.01), trails B (199s vs. 228s; P<0.01), digit symbol (31.5 vs. 37; P<0.01), and Mini-Mental State Examination (MMSE) (24 vs 26; P<0.001). There were no associations between 25OHD and memory tests. Factor analysis of cognitive tests yielded factors for memory, executive function, and attention/processing speed. After covariate adjustment, 25OHD was associated with the executive function factor (beta= 0.01; P<0.01), but not memory (beta= -0.001; P<0.8) or attention/processing speed (beta= 0.01; P<0.16). 25OHD is positively associated with cognitive performance, particularly with measures of executive function in this elderly population.