JMIR Publications

ABSTRACT

Background:

Spatial disorientation is one of the earliest and most distressing symptoms seen in Alzheimer’s disease (AD) patients, and can lead to them getting lost in the community. Although being a prevalent problem worldwide and associated with various negative consequences, very little is known about the extent to which outdoor navigation patterns of AD patients explain why spatial disorientation occurs for them even in familiar surroundings.

Objective:

Our objectives were to a) understand the outdoor navigation patterns of AD patients in different conditions (alone vs. accompanied; disoriented vs. not disoriented during the study) and b) investigate whether AD patients experienced spatial disorientation when navigating through environments with a high outdoor landmark density and complex road network structure (road intersection density, intersection complexity, orientation entropy).

Methods:

We investigated the outdoor navigation patterns of community-dwelling AD patients (n = 15) and age-matched healthy controls (n = 18) over a two-week period using global positioning system (GPS) tracking and trajectory mining analytical techniques. Here for the patients, information on whether any spatial disorientation behaviour occurred during this tracking period was also recorded. We also used a spatial buffer methodology to capture the outdoor landmark density and features of the road network in the environments that the participants visited during the tracking period.

Results:

The AD patients had similar outdoor navigation patterns to the controls when they were accompanied, however when they were alone, they had significantly fewer outings per day (total outings, P < .001; day outings, P = .003; night outings, P < .001), lower time spent moving per outing (P = .001), lower total distance covered per outing (P = .009), lower walking distance per outing (P = .02) and lower mean distance from home per outing (P = .004). Our results did not identify any mobility risk factors for spatial disorientation. We also found that the environments visited by patients that experienced disorientation vs. those who maintained their orientation during the tracking period did not significantly differ in outdoor landmark density (P = .60) or road network structure (road intersection density, P = .43; intersection complexity, P = .45; orientation entropy, P = .89).

Conclusions:

Our findings suggest that when alone, AD patients restrict the spatial and temporal extent of their outdoor navigation in the community, to successfully reduce their perceived risk of spatial disorientation. Future research is required to identify which of these individuals may be at an actual high risk for spatial disorientation as well as to explore the implementation of healthcare measures to maintain the safety and autonomy of AD patients on outings alone in the community.