Influence of visual stimuli on spatial navigation and memory of MCI, Alzheimer's disease patients and healthy control subjects

Abstract

Topographical disorientation is a frequent issue in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). Such impairments are replicated with virtual reality analogs of large-scale spatial navigation tasks. Objective: to evaluate whether visual cues are helpful for virtual spatial navigation and memory in AD and MCI patients. Twenty AD patients, 18 MCI patients and 20 age-matched healthy controls (HC) were included. All the participants had to reproduce actively a path including 5 intersections with one landmark at each that they had seen before passively. Three cueing conditions for navigation were proposed: salient landmarks, directional arrows and a map. A path without visual cues served as control condition. Navigation time and number of trajectory mistakes were recorded. After navigation, free recall and recognition of landmarks, landmarks ordering, choice of direction at each intersection and choice of patho outline were assessed. With the presence of directional arrows, no significant difference was found between groups concerning the number of trajectory mistakes and navigation time. The number of trajectory mistakes did not differ significantly between AD patients and MCI patients on the path with arrows, the path with salient landmarks and the path with a map. There were significant correlations between the number of trajectory mistakes under the arrow condition and executive tests (TMT and FAB), and between the number of trajectory mistakes under the salient landmark condition and memory tests (FCSRT 16 items and forward verbal span). Visual cueing such as directional arrows and salient landmarks appears helpful for spatial navigation and memory tasks in AD and MCI patients. These visual cueing offers new research avenues for neurorehabilitation, such as the use of augmented reality in real-life settings to support the navigational capabilities of MCI and AD patients.