Spatial Navigation Issues May Be an Early Alzheimer’s Sign
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Memory loss may not always be the first warning sign for Alzheimer’s disease. A new study suggests that some people who develop Alzheimer’s may struggle with spatial navigation long before they have other telltale symptoms of dementia.
For the study, scientists examined so-called spatial navigation skills — or the ability to recall a route followed before — for 100 cognitively healthy middle aged adults who were at risk for Alzheimer’s disease because of a family history, a genetic predisposition, or lifestyle factors such as a lack of physical activity. Scientists estimated that all the study participants were about 25 years younger than the age when they would be expected to experience the onset of dementia.
To assess spatial navigation skills, researchers had all the participants complete a series of walking tests while wearing virtual reality goggles. First, everyone 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.
“Spatial navigation is one of the earliest cognitive domains to be affected by Alzheimer’s disease,” says Vaisakh Puthusseryppady, PhD, of the spatial neuroscience lab at the University of California in Irvine.
“The reason for this is that Alzheimer’s pathology usually first appears in regions of the brain that function to help us navigate,” says Dr. Puthusseryppady, who wasn’t involved in the new study.
Participants Had No Other Evidence of Memory Loss
In the study, participants scored well on cognitive tests and didn’t show any evidence of memory loss or other typical signs of Alzheimer’s disease.
While this suggests that spatial navigation tests might one day help catch Alzheimer’s earlier, more research is still needed to pinpoint how to use this testing to benefit patients, because people may not realize they have challenges with this skill, says the senior study author, Dennis Chan, MD, PhD, a professor and neurologist at the institute of cognitive neuroscience at University College London.
“In real life people may not notice the change, since they will subconsciously adopt a different strategy to compensate, such as using landmarks for navigation, or relying on aids like Google Maps,” Dr. Chan says.
It’s also possible that performance in a lab wearing virtual reality headsets may not always be a perfect reflection of what might happen to people going about their daily lives, says Sandra Bond Chapman, PhD, a professor and the chief director of the Center for BrainHealth at the University of Texas at Dallas, who wasn’t involved in the new study.
Forgoing Google Maps to Get to Familiar Places Could Help Keep the Brain Sharp
“Virtual reality is likely to be well correlated with real life spatial navigation when it comes to unfamiliar places,” Dr. Chapman says.
But familiar environments like our homes and neighborhoods may be easier to navigate because of the routines connected to moving through these spaces regularly, Chapman says. “Such habits are routinized in other subcortical regions of the brain which may be less vulnerable to the disease,” Chapman notes. “Therefore, a person may be able to continue to function in familiar routes despite the disease being present, even with involvement of the parietal lobes.”
There are still some things people can do to keep their navigation skills sharp — starting with observing their surroundings instead of relying on their smartphone to get places, says Scott Hayes, PhD, an associate professor of psychology at the Ohio State University, in Columbus, who wasn’t involved in the new study.
“One will not remember details or have the ability to navigate if they are not attending to the relevant information in the first place,” Dr. Hayes says.
Beyond this, it’s possible to protect brain health by maintaining a physically and socially active lifestyle and following a healthy diet, Hayes adds. That’s because exercise can improve function in the same regions of the brain that play a role in spatial navigation.
“Optimizing both physical and mental health can have beneficial effects for potentially slowing Alzheimer’s related brain and cognitive decline,” Hayes says.
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