Dual-Task Gait and Alzheimer's Disease Genetic Risk in Cognitively Normal Adults: A Pilot Study.

Background: Dual-task paradigms, in which an individual performs tasks separately and then concurrently, often demonstrate that people with neurodegenerative disorders experience more dual-task interference, defined as worse performance in the dual-task condition compared to the single-task condition. Objective: To examine how gait-cognition dual-task performance differs between cognitively normal older adults with and without an APOE epsilon 4 allele. Methods: Twenty-nine individuals ages 60 to 72 with normal cognition completed a dual-task protocol in which walking and cognitive tasks (executive function, memory) were performed separately and concurrently. Fourteen participants carried APOE epsilon 4 alleles (epsilon 3/epsilon 4 or epsilon 2/epsilon 4); fifteen had APOE genotypes (epsilon 2/epsilon 2, epsilon 2/epsilon 3, or epsilon 3/epsilon 3) associated with lower risk of Alzheimer's disease (AD). Results: The two risk groups did not differ by age, sex, race, education, or gait or cognitive measures under single-task conditions. Compared to low risk participants, APOE epsilon 4 carriers tended to exhibit greater dual-task interference. Both the memory and executive function tasks resulted in dual-task interference on gait, but effect sizes for a group difference were larger when the cognitive task was executive function. In the dual-task protocol that combined walking and the executive function task, effect sizes for group difference in gait interference were larger (0.62-0.70) than for cognitive interference (0.45-0.47). Discussion: Dual-task paradigms may reveal subtle changes in brain function in asymptomatic individuals at heightened risk of AD.