Washington University researchers suggest that difficulties in establishing cognitive maps of new surroundings might indicate the onset of Alzheimer’s disease long before a clinical diagnosis. The findings suggest that navigational tasks can be a powerful new tool for early detection of Alzheimer’s disease-related changes.
The research paper, “Spatial Navigation in Preclinical Alzheimer’s Disease,” was published in the Journal of Alzheimer’s Disease.
Previous studies have demonstrated that navigational deficits are characteristic of early-stage Alzheimer’s disease (AD). Researchers theorize these deficits may be associated with hallmarks of the disease, namely amyloid beta plaque build-up and tau protein abnormalities, and also shrinkage in certain brain areas such as the hippocampus, a brain region associated with long-term memory storage, recognition of new surroundings, and the creation of cognitive maps. Despite the comprehensive documentation of such deficits, navigational abilities in preclinical Alzheimer’s have not been examined.
Researchers evaluated spatial navigation performance consisting of route-learning and cognitive map building, using a virtual maze navigation experiment. The assessment was performed in three different groups of individuals: 42 people without preclinical AD (clinically normal), 13 people clinically normal with preclinical AD, and 16 patients with early-stage symptomatic AD. The groups were determined through a biomarker test of cerebrospinal fluid, and preclinical Alzheimer’s was defined based on amyloid beta levels in the fluid (below 500 pg/ml).
According to results, preclinical Alzheimer’s was associated with difficulties in way-finding strategies, but not route-learning strategies. These patients scored lower on their ability to learn the locations of objects in the environment, in comparison with the clinically normal individuals without Alzheimer’s.
“These findings suggest that the wayfinding difficulties experienced by people with preclinical Alzheimer’s disease are in part related to trouble acquiring the environmental information,” senior author and Associate Prof. Denise Head said in a news release.“While they may require additional training to learn new environments, the good news here is that they seem to retain sufficient information to use a cognitive map almost as well as their cognitively normal counterparts.”
Despite some study limitations, such as small sample size, researchers believe aspects of spatial navigation, namely route finding performance, have moderate specificity and sensitivity for detection of early cognition deficits in Alzheimer’s.
“This pattern is consistent with decrements in hippocampal integrity prior to changes in the caudate,” Head said. “These findings suggest that navigational tasks designed to assess a cognitive mapping strategy could represent a powerful tool for detecting the very earliest Alzheimer’s disease-related changes in cognition.”