Background: The objective of this study was to examine the association between 25-hydroxyvitamin D, 25(OH)D, and cognitive function.
Methods: A cross-sectional investigation of 25(OH)D and cognition was completed in 377 black and 703 non-black (mainly Caucasian) elders (65-99 years) participating in the nutrition and memory in elders study. Participants underwent a comprehensive neuropsychological battery, and 25(OH)D concentrations were obtained.
Results: More than 65% of elders had suboptimal 25(OH)D concentrations (< or =20 ng/mL or < or =50 nmol/L). Approximately 18% were deficient in 25(OH)D (<10 ng/mL or <25 nmol/L). After adjusting for age, sex, race, body mass index, education, center, kidney function, seasonality, physical activity, and alcohol use, 25(OH)D was associated with better performance on trails A (beta = -0.49, p < .03), trails B (beta = -0.73, p < .02), digit symbol (beta = 0.19, p < .001), matrix reasoning (beta = 0.04, p < .02), and block design (beta = 0.07, p < .04) tests. Associations remained after adjustment for homocysteine, apoE4 allele, plasma B vitamins, and multivitamin use (y/n). 25(OH)D concentrations >20 ng/mL were associated with better performance on tests of executive function, including trails A (80.5 vs 95, p < .05), trails B (205s vs 226s, p < .05), matrix reasoning (7.8 vs 7.0, p = .03), and digit symbol (31.5 vs 37, p < .01). There were no associations between 25(OH)D and memory tests. Factor analysis yielded factors for memory, executive function, and attention/processing speed. After adjustment, 25(OH)D was associated with the executive function (beta = 0.01, p < 0.01) and attention/processing speed factors (beta = 0.01, p = .03), but not the memory factor (beta = -0.001, p = 0.65).
Conclusions: 25(OH)D was positively associated with cognitive performance, particularly with measures of executive function in this elderly population.