P2-220: Gait impairments in dementia subtypes: Considering the impact of environmental context

R. Mc Ardle; B. Galna; S. Del Din; A.J. Thomas; L. Rochester

doi:10.1016/j.jalz.2019.06.2627

Background Gait is a potentially useful clinical tool to aid early diagnosis of dementia. Unique signatures of gait have been shown to discriminate dementia subtypes, such as Alzheimer's disease (AD) and Lewy body disease (LBD; including dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD)), from each other and normal ageing when assessed using “gold-standard” methodology, such as instrumented walkways. Body-worn monitors, such as tri-axial accelerometers, may allow inexpensive measurement of gait in clinical environments, and provide a more ecologically-valid picture of gait in free-living environments, i.e. home and community. The aim of this study was to explore the impact of the environment on gait characteristics for distinguishing AD and LBD from each other and controls. Methods 99 participants were recruited; 32 AD ((mean±SD) Age:77±6; MMSE:23±4), 28 DLB (Age:76±6; MMSE:24±4), 14 PDD (Age:78±6; MMSE:24±4) and 25 controls (Age:74±9; MMSE:29±1). Dementia subtypes ranged from mild cognitive impairment to moderate dementia. A tri-axial accelerometer (Axivity AX3) recorded gait data over six 10-metre walks in the lab, and continuously over seven days in free-living environments. One-way ANOVAs and non-parametric equivalents assessed group differences. Results Preliminary results show that all disease groups had impaired gait compared to controls (p≤.05) in both lab and free-living environments. In the lab, the PDD group demonstrated greater variability and asymmetry of gait (p≤.05) compared to AD and DLB, and in free-living by shorter steps and greater variability of gait (p≤.05). There were no differences between AD and DLB in the lab, however, people with AD had a significantly more asymmetric step length than DLB (p=.017, AUC=.677) in free-living environments. Conclusions This study is the first to provide evidence that gait can distinguish different disease subtypes from normal ageing using inexpensive body-worn monitors. It also highlights the influence of the environment on patterns of gait impairment. Free-living gait analysis may provide a more accurate and discriminative reflection of gait impairment in different disease subtypes, and therefore be a useful clinical tool to aid early differential diagnosis. Different methods of gait analysis may provide different results; future work should validate accelerometery outcomes with gold-standard instruments in the described populations.

P2-220: Gait impairments in dementia subtypes: Considering the impact of environmental context

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