Full length articleCognitive function and walking velocity in people with dementia; a comparison of backward and forward walking
Introduction
Worldwide an estimated 46 million people live with dementia. The syndrome causes not only emotional and physical distress for the affected and their families, but also leads to extensive socio-economic costs [1]. Walking dysfunction is common within this population and increases with disease severity [2]. Impairments in walking and balance seem more obvious in people with for example vascular dementia (VaD) or Parkinson disease dementia (PDD), than in people with Alzheimer’s disease (AD) [2], [3]. Impaired walking performance manifests as slower velocity, lower cadence, shorter stride length and more time spent in double support [4], [5]. Walking requires higher-level cognitive control, in particular executive function, which is impaired in people with dementia and may contribute to this dysfunction [6].
The decline in walking velocity that comes with ageing appears to differ with direction and is more pronounced in backward walking (BW) than forward walking (FW) [7]. Being able to take steps backward is crucial when performing activities of daily living (ADL) such as backing up to a chair or moving away from the refrigerator door when closing it. Older people not only increase their walking variability more in BW than in FW, but also walk more slowly compared with younger or middle aged people [7]. Studies in people with Parkinsońs disease have shown that BW requires more proprioception [8] and attention [9] than FW. In addition, when older people with a history of falling were compared to those without, the former group was shown to have a slower BW velocity [7]. To avoid falling while walking it is common to use a walking aid, but the consequence is two-fold. On one hand a walking aid offers a larger base of support and reduces weight-bearing, which facilitates ambulation [10], but on the other hand many people find it hard to navigate in ADL, e.g. when opening a door in the opposite direction [11]. It is unclear how much cognitive resources a walking aid requires [10], [12], but people with AD appears to walk slower when maneuvering a walking aid during complex movements, suggesting that the increased cognitive demand has a cost on gait [12].
Despite the research verifying a link between walking velocity and cognition on the path leading from being a healthy older person to having mild cognitive impairment and early stage dementia [13], [14], less is known of what happens to this association when it comes to more severe dementia and dementia subtypes [15]. There is, to our knowledge, no previous research on BW velocity in this population. With this in mind, the primary aim of this study was to investigate if walking velocity in FW and BW respectively, was associated with global cognition and executive function in people with dementia with cognitive impairments ranging from mild to moderately severe. The hypothesis being that walking velocity would associate with both global cognition and executive function. The secondary aim was to investigate whether the association differed according to dementia type or use of walking aid.
Section snippets
Method
The present study had a cross-sectional design and included baseline measurements of participants from the Umeå Dementia and Exercise (UMDEX) Study [16]. Participants were recruited from 16 nursing homes in Umeå, Sweden, including both general and dementia special care units. Physiotherapists and physicians screened 864 people, of which 161 were included in this study, see Fig. 1. Inclusion criteria were a diagnosed dementia disorder [17], aged ≥65 years, dependent on assistance in ≥1 personal
Results
Baseline characteristics of the 161 participants are presented in Table 1. The mean age was 85.5 years and 124 (77.0%) were women. Sixty-three participants (39.1%) had AD and 98 participants (60.9%) had non-AD. In the AD subgroup, 37 participants (58.7%) used a walking aid as compared with 84 participants (85.7%) in the Non-AD subgroup. Participants walked on average twice as fast forward (0.47 m/s) than backward (0.23 m/s). Analyses showed a correlation between FW and BW velocity (r = 0.713, p <
Discussion
To our knowledge this is the first study to investigate the association between cognition and gait velocity in both forward and backward walking in people with dementia. After comprehensive adjustment for potential confounders, executive cognitive function was found to associate with self-selected FW and BW velocity, while global cognitive function was associated with backward walking only. An interaction effect was observed according to use of walking aid, with the association between
Conclusion
In this study of people with dementia with mild to moderately severe cognitive impairment, results indicated that executive cognitive function was important for walking velocity, both forward and backward. Global cognitive function was only independently associated with backward walking, perhaps due to it being more cognitively demanding. The association between backward walking velocity and executive function differed according to use of walking aids, which appeared to attenuate the
Conflict of interest
None.
Acknowledgments
The study was supported by the Swedish Research Council (grant numbers K2009-69P-21298-01-4, K2009-69X-21299-01-1, K2009-69P-21298-04-4, K2014-99X-22610-01-6); Forte − Swedish Research Council for Health, Working Life and Welfare (formerly FAS − Swedish Council for Working Life and Social Research, grant number 2012-0775); the Vårdal Foundation; the Swedish Dementia Association; the Promobilia Foundation; the Swedish Society of Medicine; the Swedish Alzheimer Foundation; the County Council of
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