Effect of dual-tasking on walking and cognitive demands in adults with Alzheimer's dementia experienced in using a 4-wheeled walker

Background: Learning to walk with a 4-wheeled walker increases cognitive demands in people with Alzheimer's dementia (AD). However, it is expected that experience will offset the increased cognitive demand. Current research has not yet evaluated gait in people with AD experienced in using a 4-wheeled walker under complex gait situations. Research question: What is the effect of dual-task testing on the spatial-temporal gait parameters and cognitive performance of people with AD experienced with a 4-wheeled walker? Methods: Twenty-three adults with mild to moderate AD (87.4 ± 6.2 years, 48 % female) and at least 6 months of walker use experience participated. Three walking configurations: 1) straight path (SP), 2) Groningen Meander Walking Test (GMWT), and 3) Figure of 8 path (F8) were tested under two walking conditions: 1) single-task (walking with aid) and 2) dual-task (walking with aid and completing a cognitive task). Tri-axial accelerometers collected velocity, cadence and stride time variability (STV). Gait and cognitive task cost were the percentage difference between single-task and dual-task conditions. Two-way repeated measures ANOVAs were used to answer the study question. Results: A significant interaction between walking configuration and condition was found for velocity (p = 0.002, ω² = 0.36), cadence (p = 0.04, ω² = 0.15) and STV (p < 0.001, ω² = 0.53). Velocity and cadence decreased and STV increased with increasing walking configuration complexity and upon dual-tasking. Dual-task gait and cognitive task cost deteriorated in all walking configurations, but gait was prioritized in the GMWT and F8 configurations. Despite familiarity, experienced walker users with AD exhibit impaired gait when walking in complex situations which increases falls risk. Upon dual-task, individuals with AD self-prioritized a posture-first strategy in complex configurations. Significance: Dual-task testing in experienced users results in slower walking, fewer steps and increased STV, which increases falls risk in people with mild to moderate AD and becomes most pronounced in complex environments.