Dual-Task Complexity Affects Gait in People With Mild Cognitive Impairment: The Interplay Between Gait Variability, Dual Tasking, and Risk of Falls

Montero-Odasso M, Muir SW, Speechley M. Dual-task complexity affects gait in people with mild cognitive impairment: the interplay between gait variability, dual tasking, and risk of falls. Arch Phys Med Rehabil 2012;93:293-9. Objective: To determine the effect of 2 different dual tasks on gait variability in people with mild cognitive impairment (MCI) compared with control subjects. Design: Cross-sectional study. Setting: Memory clinic at a university hospital. Participants: Older adults with MCI (n=43) and cognitively normal control subjects (n=25) from the community. Gait was assessed under single (usual walking) and dual tasking (naming animals and subtracting serial 7s), using an electronic walkway. Interventions: Not applicable. Main Outcome Measures: The dependent variable was the coefficient of variation of gait variability, a marker of gait stability and an established risk factor for falls. Two-way repeated-measures analysis of variance was used to examine main effects (group, task) and their interaction. Results: A significant difference was found within and between groups (P=.016) of increasing gait variability as dual-task complexity increased. Gait velocity decreased within groups as dual-task complexity increased. The magnitude of increased gait variability across tasks was greater for the MCI group (2.68%-9.84%) than for the control group (1.86%-3.74%), showing a significant between-group difference (P=.041). Conclusions: Dual-task load significantly increased gait variability in the MCI group compared with the control group, an effect that was larger than the changes in gait velocity. The magnitude of this impairment on gait stability was related to the complexity of the dual task applied. Our findings help to explain the high risk of falls recently described in older adults with MCI, and may help in the identification of fall risk in cognitively impaired persons.