Assessing the Relationship between Vitamin D Status and Impairments in Cognitive and Physical Performance in Older Adults Using a Dual Task Physical Performance Test

• Published in: The journal of prevention of Alzheimer's disease Vol. 4; no. 1; p. 29
• Main Authors: Lopez, J, Campa, A, Lewis, J E, Huffman, F G, Liuzzi, J P, Li, T, Martinez, A H, Ferris, S M, Rasul, A, Farooqi, A, Lopez Medrano, A M, Atlas, S E, Tiozzo, E, Konefal, J, Woolger, J M
• Format: Journal Article
• Language: English
• Published: Switzerland 01.01.2017
• Subjects: Analysis of Variance; Cognitive Dysfunction - blood; Cross-Sectional Studies; Executive Function - physiology; Humans; Logistic Models; Mathematical Concepts; Middle Aged; Movement Disorders - blood; Movement Disorders - psychology; Neuropsychological Tests; Psychomotor Performance - physiology; Vitamin D - analogs & derivatives; Vitamin D - blood; Vitamin D Deficiency - blood; Vitamin D Deficiency - psychology; Walking Speed - physiology; older adult; physical performance; Vitamin D status; dual task; executive function
• ISSN: 2426-0266
• DOI: 10.14283/jpad.2016.114

Vitamin D deficiency has been associated with an increased risk of falls in older adults. Several studies have demonstrated an association between vitamin D deficiency and gait and cognitive impairments, which are two risk factors for falls in the elderly. There is lack of research about the role of vitamin D in cognitive function in the context of mobility. The purpose of this study was to evaluate the association between vitamin D status with the age-related changes in mobility through higher order cognitive function using a dual task physical performance test. Cross-sectional. Community-dwelling older adult population located in Miami, Fl. Healthy participants over the age of 55 (n=97) who participated in the parent interventional study. Participants completed assessments that included serum levels of vitamin D, surveys, and dual task physical performance tests. Spearman's correlations, independent t-tests, repeated measures ANOVAs and multiple logistic regressions were used to examine the relationship between vitamin D insufficiency (25-hydroxyvitamin D <30 ng/ml) and sufficiency (≥30 ng/ml) and dual task physical performance variables. The significance level was set at α=0.05. There were no significant associations between vitamin D insufficiency and gait velocity during either task. Using Spearman correlations, slower single (P=0.011) and dual task counting rates (P=0.006) were significantly associated with vitamin D insufficiency. Independent t-tests showed dual and single task counting rates were significantly lower in the vitamin D insufficient group compared to the sufficient group (P=0.018 and P=0.028, respectively). The results for the ANOVAs indicated that velocities and counting rates were not significantly different by vitamin D status (Wilk's Lambda =0.999; F (1, 95) =.11, P=.740) (Wilk's Lambda =.999, F(1,95)=.13, P=.718). Vitamin D status was not significantly associated with dual task physical performance (defined as the difference in dual and single task) in gait velocity (OR=1.00, 95% CI: 0.98; 1.02, P=0.772) and counting rate (OR=1.684, 95% CI: 0.15; 19.57, P=0.677), when controlling for confounders. Since counting backward is a mental tracking task, which is a component of executive function, our results suggest a relationship between vitamin D insufficiency and executive dysfunction. Executive dysfunction has been previously associated with fall risks in the elderly, and it could be a possible mediator between vitamin D and falls. Our data suggest that cognition may play a significant role in vitamin D's influence on falls, while motor function may play a lesser role.