The effects of a concurrent motor task on walking in Alzheimer's disease

•We assess the effects of a motor dual-task on gait measures of Alzheimer participants.•Carrying a tray and empty glasses produced slowed and more variable gait measures.•Decrease in velocity exceeded a minimum clinically detectable change score.•Motor dual task effects were greater on spatial than temporal variables.•The added motor task was feasible in people with moderate to severe cognitive impairment.

The important relationship between cognition and gait in people with dementia has been explored with dual-task studies using added cognitive tasks. Effects of less commonly studied but also attention-dividing motor dual-tasks are important to assess in this group as they are common in everyday function and may affect gait differently from cognitive dual-tasks. They may also be easier to comprehend allowing their application with more severe cognitive impairment. The aim of this study was to evaluate the effects and feasibility of a motor dual-task (MDT) on gait measures in people with Alzheimer's disease (AD). Thirty people (15 men, mean age ± SD, 80.2 ± 5.8 years) with a diagnosis of probable AD (MMSE range 8-28) walked on an electronic walkway (i) at self-selected comfortable pace and (ii) at self-selected comfortable pace while carrying a tray and glasses. The MDT produced significant decreases in velocity (Baseline = 111.5 ± 26.5 cm/s, MDT = 96.8 ± 25.7 cm/s, p < 0.001) and stride length (Baseline = 121.4 ± 21.6 cm, MDT = 108.1 ± 21.0 cm, p < 0.001) with medium effect sizes, and increased stride time (Baseline = 1.11 ± 0.11 s, MDT = 1.14 ± 0.12 s, p = 0.001) with small effect size. Measures of spatial (Baseline = 3.2 ± 1.0%, MDT = 3.9 ± 1.5%, p = 0.006) and temporal (Baseline = 2.4 ± 0.8%, MDT = 2.8 ± 0.8%, p = 0.008) variability increased with the motor dual-task, with medium effect sizes. A trend for motor dual-task changes in gait measures to increase with greater disease severity did not reach significance. The tray-carrying task was feasible, even for participants with severe cognitive decline. Further comparison of different types of motor and cognitive dual-tasks may contribute to development of a framework for clinical intervention to improve reduced dual-task walking capacity in people with AD.