It turns out that we may be able to predict Alzheimer's disease by looking at how people navigate. Scientists have found that a person's navigational skills decline before other symptoms of Alzheimer's appear.
Previous research has shown that navigation problems begin early in individuals with Alzheimer's. This could be associated with the build up of amyloid plaques and tau tangles in addition to other signs of deterioration and shrinkage in the brain.
In this latest study, the researchers used a virtual maze navigation experiment to look at whether specific problems with route learning and cognitive map building, which involve the caudate and the hippocampus, could be detected in preclinical Alzheimer's. More specifically, the researchers looked at two distinct forms of spatial representation. These included egocentric navigation, where people rely on landmarks for well-worn routes, and allocentric navigation, where people become familiar with "big picture" surroundings and create a mental map.
The researchers separated volunteers into three groups. They then tested their ability to navigate a virtual maze consisting of a series of interconnected hallways with four wallpaper patterns and 20 landmarks on a computer. The volunteers were given 20 minutes to move through the maze and were then tested on their ability to recreate their route or find their way back to specific landmarks.
"People with cerebrospinal markers for preclinical Alzheimer's disease demonstrated significant difficulties only when they had to form a cognitive map of the environment-an allocentric, place-learning navigation process associated with hippocampal function," said Denise Head of Washington University and one of the researchers involved in the study. "The same preclinical Alzheimer's disease group showed little or no impairment on route learning tasks- an egocentric navigation process more closely associated with caudate function."
The results show that those with preclinical Alzheimer's disease have trouble acquiring environmental information. This, in turn, may mean that they might need additional training to learn new environments. With that said, they still have enough information to use a cognitive map almost as well as others who are not suffering from preclinical Alzheimer's.
The findings were published in the April 2016 issue of the Journal of Alzheimer's Disease.
