Uneven surface and cognitive dual-task independently affect gait quality in older adults

Abstract

Background: Real-world mobility involves walking in challenging conditions. Assessing gait during simultaneous physical and cognitive challenges provides insights on cognitive health.

Research question: How does uneven surface, cognitive task, and their combination affect gait quality and does this gait performance relate to cognitive functioning?

Methods: Community-dwelling older adults (N = 104, age=75 ± 6 years, 60 % females) performed dual-task walking paradigms (even and uneven surface; with and without alphabeting cognitive task (ABC)) to mimic real-world demands. Gait quality measures [speed(m/s), rhythmicity(steps/minute), stride time variability (%), adaptability (m/s²), similarity, smoothness, power (Hz) and regularity] were calculated from an accelerometer worn on the lower back. Linear-mixed modelling and Tukey analysis were used to analyze independent effects of surface and cognitive task and their interaction on gait quality. Partial Spearman correlations compared gait quality with global cognition and executive function.

Results: No interaction effects between surface and cognitive task were found. Uneven surface reduced gait speed(m/s) (β = -0.07). Adjusted for speed, uneven surface reduced gait smoothness (β = -0.27) and increased regularity (β = 0.09), Tukey p < .05, for even vs uneven and even-ABC vs uneven-ABC. Cognitive task reduced gait speed(m/s) (β = -0.12). Adjusted for speed, cognitive task increased variability (β = 7.60), reduced rhythmicity (β = -6.68) and increased regularity (β = 0.05), Tukey p < .05, for even vs even-ABC and uneven vs uneven-ABC. With demographics as covariates, gait speed was not associated with cognition. Gait quality [lower variability during even-ABC (ρ_p =-.31) and uneven-ABC (ρ_p =-.28); greater rhythmicity (ρ_p between.22 and.29) and greater signal-adaptability AP (ρ_p between.22 and.26) during all walking tasks] was associated with better global cognition. Gait adaptability during even (ρ_p =-0.21, p = 0.03) and uneven(ρ_p =-0.19, p = 0.04) walking was associated with executive function.

Significance: Surface and cognitive walking tasks independently affected gait quality. Our study with high-functioning older adults suggests that task-related changes in gait quality are related to subtle changes in cognitive functioning.

Keywords: Accelerometry; Cognitive function; Dual tasks; Gait; Healthy aging.

Fig. 1

Pare-wise comparisons of gait variables across the four conditions. Tukey (p<.05). Blue lines indicate statistically significant differences. A) Pace (Gait speed) reduces as the difficulty of task increases B) Variability (stride time variability CoV) increases due to cognitive task. The standard deviation in variability increases with task complexity. C) Rhythmicity (cadence) reduces due to cognitive task on both even and uneven surfaces D) Adaptability (standard deviation AP) is not significantly affected during dual-task walking, although it shows increased trending effects on uneven surface and decreased effects during cognitive task E) Similarity (cross-correlation AP-V) reduces on uneven surface F) Power (peak frequency V) reduces significantly due to cognitive task, the effect is stronger on even surface. G) Smoothness (harmonic ratio AP) reduces on uneven surface H) Regularity (entropy rate) increases due to uneven surface and cognitive dual-task, the effect is stronger due to surface change