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

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 ([less than or equal to]20 ng/mL or [less than or equal to]50 nmol/L). Approximately 18% were deficient in 25(OH)D (< 10 ng/mL or 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. Alter 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. Key Words: Cognitive function--Vitamin D--Elderly people--Dementia.