ReviewCognitive motor interference while walking: A systematic review and meta-analysis
Research highlights
▶ Gait control places demand on cognitive centres of the brain. ▶ Cognitive tasks that involve internal interfering factors disturb gait. ▶ Speed is a sensitive measure of gait performance under dual-task conditions.
Introduction
Independent, secure, fast, and safe gait is a major concern amongst the elderly and individuals with neurological disorders (Snijders et al., 2007). Purposeful locomotion requires the ability to adapt to meet individual goals and environment's burdens, and commonly involves performing concurrent cognitive tasks while walking, such as recalling a shopping list or attending to a conversation. Therefore, gait performance cannot be a series of rote repetitions with each step exactly like the last because the everyday environment is considerably variable. Instead, gait is a complex task that places demands on sensory and cognitive systems (Sheridan and Hausdorff, 2007).
Empirical evidence from brain imaging studies has revealed activation of areas related to higher cognitive control during actual (Harada et al., 2009, Miyai et al., 2001, Suzuki et al., 2004), imagined (Bakker et al., 2008, Iseki et al., 2008, Jahn et al., 2004, Malouin et al., 2003) and simulated (Francis et al., 2009, Huda et al., 2008, Sahyoun et al., 2004) gait. Similarly, results from lesion-behaviour studies provide evidence for the essential role that the higher cognitive control systems have in gait control (Rosano et al., 2008, Rosano et al., 2005, Thompson, 2001, Whitman et al., 2001).
The relative cognitive demand of gait control can be explored using dual-task methodology, where performance changes in either or both of the concurrent tasks indicate the extent of their cognitive demand (Abernethy, 1988). Recently, the usage of dual-task methodology to assess the interplay between gait and cognition has been a growing topic of research (Woollacott and Shumway-Cook, 2002, Yogev-Seligmann et al., 2008). Moreover, dual-task-related changes have been reported amongst different populations for a wide range of cognitive tasks and in the various components of gait performance (Supplementary tables). However, whether the observed dual-task-related gait changes are systematically related to methodological variations remains unclear and complicates firm conclusions being drawn from this literature.
The primary purpose of this meta-analysis review is to quantitatively assess cognitive interference on gait performance during normal walking as measured by dual-task methodology. We reviewed experimental single group studies that measured gait performance with and without performing concurrent cognitive task. Better understanding of the interaction between gait and cognitive functions would benefit both researchers and professionals to plan appropriate interventional trials and inform clinical decision-making. In particular, this review aims to investigate methodological variations that may explain dual-task-related changes in gait performance by addressing the following questions: (a) what is the effect of different cognitive dual tasks on various spatio-temporal gait measures? (b) to what extent is dual-task effect on gait modified by cognitive task domain, participant age, and cognitive or neurological impairment?
Section snippets
Literature search and inclusion criteria
A computer based search was carried out using the electronic bibliographic databases: Cochrane, EMBASE, PubMed, and by checking references found in retrieved articles. The search included papers and abstracts up to the end of 2009. The search strategy included the following key words: gait/walking and executive functions; gait/walking and attention; gait/walking and working memory; gait/walking and dual-task/tasking; gait/walking and cognition; gait/walking and talking.
Study selection
Two reviewers (EA and AD)
Results
Database and reference searches identified 152 studies for consideration. Abstract examination identified 16 reviews and 2 case studies, which were excluded from further consideration (Fig. 1). After applying the inclusion criteria, 96 studies were considered for the qualitative synthesis (Supplementary data), of which 10 were excluded due to the absence of adequate data to compute effect size. To determine which outcomes had sufficient studies for pooling in a meta-analysis, first we ran
Discussion
The meta-analysis results of dual-task studies emphasize the role of high-order cognitive systems in gait control. The main findings and their implication are discussed below.
Conclusion
The amount of the existing literature that has investigated dual-task effects on gait performance reflects the importance of this research area and its potential clinical applications. Changes in speed and the relationship between age and CMI effect on gait, as well as the relationship between the level of cognitive state and CMI effect on gait are relevant for understanding gait control mechanisms. All confirmed the widely accepted notion that gait control places demand on high cognitive
Acknowledgements
This study is part of a project supported by the UK Stroke Association (TSA 2007/09) for the Movement Science Group of Oxford Brookes University. Emad Al-Yahya is supported by a grant from the University of Jordan, Amman-Jordan. We would like to thank members of the Movement Science Group for their support.
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