Full length article The effects of a concurrent motor task on walking in Alzheimer’s disease Joanne E. Wittwer a, *, Kate E. Webster a , Keith Hill b a Department of Physiotherapy, School of Allied Health, Faculty of Health Sciences, La Trobe University, Melbourne, Australia b School of Physiotherapy, Curtin University, Perth, Australia Deterioration of walking in people with Alzheimer’s disease (AD) begins early in the course of the disease [1] and includes decreased velocity, stride length and cadence together with increased stride to stride variability [2]. Gait decline is associated with increased rates of falling [3]. Gait impairment in AD is thought to be due to decline in cognitive and sensorimotor function related to the disease. It is now recognised that gait control requires cognition, particularly executive functions (e.g. planning, working memory) [4] with the degree of cognitive involvement dependant on the novelty and complexity of the gait task [4]. The progressive deterioration of executive function [4] together with the increased sensorimotor decline demonstrated in people with AD compared to controls [5], may therefore result in the slowed and more variable walking typical in people with AD, even with simple gait tasks. Other likely contributing factors are the increased cognitive load of compen- sating for sensory decline [4] and the early damage to neural structures known to control motor function [4]. The relationship between cognition and gait has been explored with dual-task studies. In people with AD, dual-task walking highlights the impact on gait of executive function impairment whereby a concurrent task produces greater deficits compared to those elicited in cognitively healthy controls [6]. Changes in gait variability during dual-task walking may predict falling in people with AD [6] and assist with diagnosis of dementia [7]. Dual-task gait studies have mostly used cognitive tasks (e.g. verbal fluency) [8]. Motor dual-tasks are also important to investigate as they are common in everyday function. They are similar to cognitive dual- tasks in that they are attention-demanding and require higher cognitive control, although different cognitive processes are likely to be involved. They may also differ by creating a greater load on sensorimotor systems due to their characteristics. For example, holding an object steady with both arms may constrain upper body and head movement, or carrying something large may alter visual information by obscuring the path ahead. Functional motor Gait & Posture 39 (2014) 291–296 A R T I C L E I N F O Article history: Received 25 March 2013 Received in revised form 12 June 2013 Accepted 26 July 2013 A B S T R A C T 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 (Base- line = 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. ß 2013 Elsevier B.V. All rights reserved. * Corresponding author at: School of Allied Health, La Trobe University, Victoria 3086, Australia. Tel.: +61 3 9479 5808; fax: +61 3 9479 5415. E-mail address: j.wittwer@latrobe.edu.au (J.E. Wittwer). Contents lists available at ScienceDirect Gait & Posture jo u rn al h om ep age: ww w.els evier.c o m/lo c ate/g aitp os t 0966-6362/$ – see front matter ß 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gaitpost.2013.07.126