Spatial Navigation in Preclinical Alzheimer's Disease

Abstract

Although several previous studies have demonstrated navigational deficits in early-stage symptomatic Alzheimer's disease (AD), navigational abilities in preclinical AD have not been examined. The present investigation examined the effects of preclinical AD and early-stage symptomatic AD on spatial navigation performance. Performance on tasks of wayfinding and route learning in a virtual reality environment were examined. Comparisons were made across the following three groups: Clinically normal without preclinical AD (n = 42), clinically normal with preclinical AD (n = 13), and early-stage symptomatic AD (n = 16) groups. Preclinical AD was defined based on cerebrospinal fluid Aβ42 levels below 500 pg/ml. Preclinical AD was associated with deficits in the use of a wayfinding strategy, but not a route learning strategy. Moreover, post-hoc analyses indicated that wayfinding performance had moderate sensitivity and specificity. Results also confirmed early-stage symptomatic AD-related deficits in the use of both wayfinding and route learning strategies. The results of this study suggest that aspects of spatial navigation may be particularly sensitive at detecting the earliest cognitive deficits of AD.

Keywords: Aging; allocentric; amyloid; caudate nucleus; egocentric; hippocampus.

Fig. 1

Wayfinding performance. A) learning phase performance; B) delay phase performance; C) Environmental Knowledge Composite. White circles = clinically normal individuals who are biomarker negative (CN biomarker−), light gray triangles = clinically normal individuals who are biomarker positive (CN biomarker+), dark gray squares = early-stage symptomatic AD individuals. Data represent estimated marginal means (controlling for covariates; see text for details), and error bars are standard error of the mean.

Fig. 2

Route learning performance. A) learning phase performance; B) delay phase performance; C) Environmental Knowledge Composite. White circles = clinically normal individuals who are biomarker negative (CN biomarker−), light gray triangles = clinically normal individuals who are biomarker positive (CN biomarker+), dark gray squares = early-stage symptomatic AD individuals. Data represent estimated marginal means (controlling for covariates; see text for details), and error bars are standard error of the mean.