A study was done at Washington University in St. Louis which indicates that, of all the warning signs that suggest Alzheimer’s may be developing, the earliest one is probably a difficulty in navigation. This is because the area of the brain that is used to help you move from one place to the next seems to be affected by the disease earlier than other areas. To understand why this is one of the first signs of Alzheimer’s, you must understand how it is that we are able to find our way around when we are in a new setting. This study on the was published in April 2016 in the Journal of Alzheimer’s Disease.
There are two ways that most people navigate. The first way, called “egocentric navigation,” is a method in which the person uses information from past experiences in order to move along a known route. This is the type of navigation you use when you are traveling a known route that you have used before. Typically, you will move from one landmark to the next—whether the landmark is a certain exit sign, a tree at a certain intersection, or something else—taking predetermined acts at each landmark and progressing from landmark to landmark sequentially.
The second method of navigation, called “allocentric navigation,” requires people to have a “big-picture” view of their surroundings, which they then populate with known landmarks. Using allocentric navigation, people can take new routes—for example, looking for a new shortcut—from one known landmark to another known landmark.
Egocentric navigation tends to rely on the brain’s ability to recall past journeys. In contrast, allocentric navigation uses the brain’s ability to create a cognitive map of the person’s surroundings.
In the study led by Denise Head, associate professor of Psychological and Brain Sciences in Arts & Sciences, researchers placed subjects in a virtual maze populated with different landmarks. Using a joystick, the subjects were able to navigate the maze, either to travel through it along a pre-specified path or to spend time exploring the maze and learning where various landmarks were.
The study results showed that people who had Alzheimer’s had little difficulty using egocentric navigation—following a pre-determined route that is already known to the person. However, when they attempted to use allocentric navigation, the subjects with Alzheimer’s displayed much more difficulty learning where certain objects in the maze were located in relation to others. This suggests that the part of the brain used for building a cognitive map may be one of the first sections to be affected by Alzheimer’s. This inability to use allocentric navigation can show up much earlier than other warning signs of Alzheimer’s.
This conclusion also seems to fit with another already-known sign of Alzheimer’s: short-term memory loss. Many people who are suffering from Alzheimer’s or dementia have no problems recalling things that happened years or even decades earlier; however, they display significant difficulty when asked to recall things that happened within the last few days or weeks. This may be because the same part of the brain that processes short-term memory is involved with creating and updating a cognitive map of one’s surroundings. Whatever the specific reason, the results of the study suggest that someone suffering from Alzheimer’s will display considerably more difficulty navigating in a new environment than someone without the disease.
A Caveat: Mere Difficulty Navigating May Not be Conclusive Evidence of Alzheimer’s
Difficulty navigating in new surroundings does not, by itself, mean that someone has Alzheimer’s. However, if someone who previously was able to use allocentric navigation without difficulty suddenly displays an inability to do so, it may be a warning sign as one of the first signs of Alzheimer’s. If you—or your elderly loved one—notice something like this beginning to take place, it is definitely worth taking a trip to the doctor for a discussion on the matter. It could be that you are witnessing the very initial stages of the onset of Alzheimer’s disease.