Abstract
People with Alzheimer's disease (AD) have characteristic problems navigating everyday environments. While patients may exhibit abnormal gait parameters, adaptive gait irregularities when navigating environments are little explored or understood. The aim of this study was to assess adaptive locomotor responses of AD subjects in a complex environment requiring spatial navigation. A controlled environment of three corridors was set up: straight (I), U-shaped (U) and dog-leg (S). Participants were asked to walk along corridors as part of a counterbalanced repeated-measures design. Three groups were studied: 11 people with posterior cortical atrophy (PCA), 10 with typical Alzheimer's disease (tAD) and 13 controls. Spatio-temporal gait parameters and position within the corridors were monitored with shoe-mounted inertial measurement units (IMUs). Hesitant steps were identified from statistical analysis of the distribution of step time data. Walking paths were generated from position data calculated by double integration of IMU acceleration. People with PCA and tAD had similar gait characteristics, having shorter steps and longer step times than controls. Hesitant steps tended to be clustered within certain regions of the walking paths. IMUs enabled identification of key gait characteristics in this clinical population (step time, length and step hesitancy) and environmental conditions (route complexity) modifying their expression.
Highlights
And common symptoms of Alzheimer’s disease (AD) are problems in spatial navigation, greatly undermining autonomy
In typical Alzheimer’s disease, initial pathological changes in medial temporal regions associated with episodic and spatial memory progress to posterior cortical regions, including those supporting visuospatial processing [2]
Step time and walking speed have been observed in people with both cognitive impairment and dementia [9], and gait changes appear to be related to the stage of the disease [10,11,12]
Summary
And common symptoms of Alzheimer’s disease (AD) are problems in spatial navigation, greatly undermining autonomy. While such problems are often associated with deficits in memory and planning, the role of dementia-related visual processing impairments in limiting navigation, in familiar environments, is often under-recognised [1]. A basic gait laboratory setting has been used to assess gait in tAD while performing a cognitive task [13, 14], this does not replicate the daily navigational challenges of people with visual and/or cognitive problems. Perceptual factors (e.g. lighting, clutter) may have a disproportionate effect on functional performance in tAD, but situations that replicate these conditions are difficult to set up in a standard gait laboratory. Creating environments with walls and confined spaces makes it very difficult to use standard opto-electronic motion capture systems, which require a line-of-sight view from the motion detection camera to the subject
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