Certain Walking Problems May Be Early Sign of Alzheimer’s Disease
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People with early Alzheimer’s disease may have a harder time than cognitively healthy individuals while navigating paths with a lot of twists and turns, a small study suggests.
For the study, scientists asked 43 people with mild cognitive impairment (a condition that can be a precursor to Alzheimer’s), 31 cognitively healthy adults in their twenties, and 33 cognitively healthy older adults to complete a walking test while wearing virtual reality goggles.
First, participants navigated a path guided by numbered cones to point them in the right direction at each turn. Then, they repeated the task under three different conditions designed to test their navigation skills: a route exactly like the one they saw before, a path with all the textures on the ground replaced by smooth surfaces, and a path without any landmarks to guide their way.
The only participants who struggled to navigate turns along the path when conditions changed were the people with mild cognitive impairment, according to study results published in Current Biology. These individuals consistently miscalculated how much to turn and experienced variability in their sense of direction while they walked. None of this happened with the younger or elderly participants who were cognitively healthy.
Why Does Alzheimer’s Affect a Person’s Ability to Navigate Turns?
“Alzheimer’s disease tends to develop first towards the back and middle of the brain and then slowly spread forward,” says Sandra Bond Chapman, PhD, a professor and chief director of the Center for BrainHealth at the University of Texas in Dallas.
“Spatial navigation depends on the parietal lobes of the brain, which are in the rear half of the brain and are in the region where the disease often strikes first,” says Dr. Chapman, who wasn’t involved in the new study.
In the study, people had to use a skill known as path navigation, which requires the brain to automatically update its understanding of where the body is physically located in its environment based on its own movements, says senior study author Neil Burgess, PhD, of the University College London Institute of Cognitive Neuroscience in England. Cognitively healthy people do this in real time as they move through the world.
Because the cognitively healthy younger and older adults all navigated the path without difficulty when visual and spatial cues were removed, the study results suggest that navigational challenges seen in the tests are unique to Alzheimer’s disease and not simply a normal result of aging, the study authors report.
Researchers Aim to Develop Practical Tests for Early Alzheimer’s
The study was small, and it wasn’t designed to prove whether or how Alzheimer’s disease might directly cause navigational difficulties. Another drawback is that results from virtual reality tests might differ from what would happen when people can use all of their senses to see, hear, and feel what’s happening in their environment to help them move accurately along a path.
Still, if more research confirms the study findings, it might help scientists develop a test for early Alzheimer’s, according to a statement by lead study author Andrea Castegnaro, PhD, of the University College London Institute of Cognitive Neuroscience.
“We aim to develop practical tests that can be easily integrated into clinical settings, considering common constraints such as limited space and time,” Dr. Castegnaro said. “Traditional navigation tests often have requirements that are challenging to meet in a clinical environment. Our research focuses on specific aspects of navigation that are more adaptable to these constraints.”
Eschewing Tools Like Google Maps May Help Protect Navigational Skills
People who want to keep their navigational abilities sharp can do this by using physical maps or landmarks to follow a route instead of simply relying on tools like Google maps, Chapman says. Although this can’t slow the progression of Alzheimer’s disease, it might still have benefits.
“It is possible to mitigate some of the negative effects of Alzheimer’s by keeping the brain stimulated, including by using spatial abilities as much as possible,” Chapman says. “Whereas it is unlikely that actively stimulating navigational skills will significantly affect the trajectory of the disease, it would be of interest to study how it could keep patients functional longer in terms of staying better oriented in navigating space.”
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