Dual-task decrements in gait: contributing factors among healthy older adults.

BACKGROUND The factors that contribute to the dual tasking (DT) changes in performance that occur when older adults walk while simultaneously performing other tasks are not well known. We hypothesized that cognitive and motor reserve (e.g., executive function [EF], postural control, and walking abilities) and affect (e.g., anxiety, depressive symptoms) influence the DT decrements (DTDs) in gait. METHODS Two hundred twenty-eight community-living, healthy older adults (mean: 76.2 +/- 4.2 years; 59% women) walked with and without DT, for example, subtracting 7s and phoneme monitoring. Mobility (e.g., the Dynamic Gait Index), cognitive function (e.g., memory, EF), and affect (e.g., Geriatric Depression Scale) were quantified. Bivariate and multivariate analyses identified factors associated with the DTD in gait speed (a general measure of locomotor function), swing time, (reflecting balance during gait), and swing time variability (a measure of stride-to-stride consistency). RESULTS Gait speed and swing time decreased (p <.001) and swing time variability increased (became worse) (p <.001) during all DTs. The DTD in gait speed was correlated with comfortable walking gait speed, but not with tests of mobility or cognitive function. The DTD in swing time variability was correlated with EF, mobility, and affect (e.g., depressive symptoms). Much of the variance in the DTDs was unexplained. CONCLUSIONS Usual walking abilities and cognitive function contribute to the DT effects on gait, but these relationships depend on specifics of the DT, the gait feature being studied, and the particulars of the cognitive domain. Meeting the everyday challenges of walking while dual tasking apparently relies on multiple factors including a consistent gait pattern and EF.