Abstract
IntroductionClinical reports describe patients with Alzheimer's disease (AD) exhibiting atypical adaptive walking responses to the visual environment; however, there is limited empirical investigation of such behaviors or factors modulating their expression. We aim to evaluate effects of lighting‐based interventions and clinical presentation (visual‐ vs memory‐led) on walking function in participants with posterior cortical atrophy (PCA) and typical AD (tAD).MethodsParticipants with PCA (n = 10), tAD (n = 9), and healthy controls (n = 12) walked to visible target destinations under different lighting conditions within two pilot repeated‐measures design investigations (Experiment 1: 32 trials per participant; Experiment 2: 36 trials per participant). Participants walked to destinations with the floorpath interrupted by shadows varying in spatial extent (Experiment 1: no, medium, high shadow) or with different localized parts of the environment illuminated (Experiment 2: target, middle, or distractor illuminated). The primary study outcome for both experimental tasks was completion time; secondary kinematic outcomes were proportions of steps identified as outliers (Experiment 1) and walking path directness (Experiment 2).ResultsIn Experiment 1, PCA participants overall demonstrated modest reductions in time taken to reach destinations when walking to destinations uninterrupted by shadows compared to high shadow conditions (7.1% reduction [95% confidence interval 2.5, 11.5; P = .003]). Experiment 2 found no evidence of differences in task performance for different localized lighting conditions in PCA participants overall. Neither experiment found evidence of differences in task performance between conditions in tAD or control participants overall. Completion time in both patient groups was longer relative to controls, and longer in PCA relative to tAD groups.DiscussionFindings represent a quantitative characterization of a clinical phenomenon involving patients misperceiving shadows, implicating dementia‐related cortico‐visual impairments. Results contribute to evidence‐based design guidelines for dementia‐friendly environments.
Highlights
Clinical reports describe patients with Alzheimer’s disease (AD) exhibiting atypical adaptive walking responses to the visual environment; there is limited empirical investigation of such behaviors or factors modulating their expression
We evaluated effects of two lighting-based interventions in participants with early-stage PCA, typical AD (tAD), and controls walking to visible destinations
For Experiment 1, inertial measurement units (IMUs) data were unavailable for all trials in one participant (PCA) and were unavailable for the last 16 trials for one participant (PCA) owing to depleted IMU battery, and for one trial for three participants
Summary
Clinical reports describe patients with Alzheimer’s disease (AD) exhibiting atypical adaptive walking responses to the visual environment; there is limited empirical investigation of such behaviors or factors modulating their expression. We aim to evaluate effects of lighting-based interventions and clinical presentation (visual- vs memory-led) on walking function in participants with posterior cortical atrophy (PCA) and typical AD (tAD). The visual environment may play an elevated role mediating everyday function in Alzheimer’s disease (AD) and other dementia syndromes This role is corroborated through clinical observations of patients overstepping perceptual variations in flooring, such as patterned carpeting or shadows, or being overly reliant on landmarks or conspicuous environmental features to support navigation.[1,2,3,4] Despite the promise of cost-effective environmental adaptations facilitating patient autonomy and safety, repeated calls for high-quality quantitative research in this area remain largely unmet,[2,5,6] and existing studies have given limited consideration to patient clinical presentation.[7]. At a relatively early stage, PCA patients may be unable to drive, read, dress independently, or reliably navigate familiar environments despite relatively preserved memory, language, and insight.[20]
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