By contributor
updated 11/15/2010 8:51:23 AM ET 2010-11-15T13:51:23

Jean Snyder says she isn't afraid of spiders, snakes or even dentists. But she is scared of one little thing: a GPS breakdown.

Snyder's 2005 Honda Odyssey is equipped with GPS, and for the last five years, Snyder hasn't looked at a map, noticed landmarks or even tried new routes to get from point A to point B. Instead, she relies on the disembodied voice of "Jackie," her GPS, to guide her.

"When it comes to finding my way, I've become a GPS zombie," says Snyder, a 47-year-old office manager in Highland Heights, Ohio."I'm sure I'm not doing my brain any favors."

Snyder might be on to something. Three studies by McGill University researchers presented at the annual meeting of the Society for Neuroscience on Sunday show that the way we navigate the world today may indeed affect just how well our brains function as we age — particularly the hippocampus, which is linked to memory.

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Navigating by landmark or on auto-pilot
Generally, to find our way, we rely on one of two strategies: The first is a so-called spatial navigation strategy, in which we build cognitive maps using things like landmarks as visual cues that not only help us determine where we are at a given point in space, but also help us plan where we need to go.

Or, we navigate by using a stimulus-response strategy, a kind of auto-pilot mode in which we turn left and right because, after some repetition, that's the most efficient way to get from A to B. If you have GPS, that uber-strategy of stimulus-response may seem quite familiar.

Those in the study who navigated spatially were shown on fMRI images to have increased activity in the hippocampus, an area of the brain believed to be involved in memory and navigation and play a role in finding shortcuts and new routes.

According to the McGill researchers, their findings suggest that the aging process involves a shift in navigational strategies. Healthy young adults tend to spontaneously use a spatial approach when navigating a virtual maze, the McGill researchers found in their studies. But most older adults used a response strategy.

That shift may lead to atrophy of the hippocampus, a risk factor for cognitive problems in normal aging and in Alzheimer's disease, explains neuroscientist Veronique Bohbot, associate professor of psychiatry at the Douglas Mental Health University Institute and McGill University. The hippocampus is one of the first brain areas to be affected by Alzheimer's disease, causing problems with memory and spatial orientation.

Use it or lose it?
But the researchers also found a greater volume of grey matter in the hippocampus of older adults who used spatial strategies. And these adults scored higher on a standardized cognition test used to help diagnose mild cognitive impairment, which is often a precursor to Alzheimer's disease. These findings suggest that using spatial memory may increase the function of the hippocampus and increase our quality of life as we age, says Bohbot. More simply: it could be a case of use it or lose it.

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Although the studies compare different groups of people and don't show causality, the findings are "plausible," explains Russell Epstein, associate professor of psychology at the University of Pennsylvania's Center for Cognitive Neuroscience.

For example, research at the University of London showed that part of the hippocampus of London taxi cab drivers is actually larger than that of a non-taxi driver control group. Despite the most experienced drivers having the most robust hippocampus, it's still not known whether finding those novel routes through London's Byzantine maze of streets caused the hippocampus to grow, or if having a robust hippocampus helps a person become a successful cab driver, explains Epstein.

Nonetheless, exercising your own hippocampus may not be a bad idea. "There is something to be said about intellectual enrichment, having some type of reserve that may be able to lessen the impact of cognitive decline," explains Rainbow Babies & Children's Hospital pediatric neurologist Dr. Max Wiznitzer, who actually prefers finding his own way sans GPS when traveling to new places.

The take-away message isn't to rip your GPS from the dashboard. Rather be smart about it, says Bohbot, noting that building cognitive maps takes “time and effort.” Her suggestion is to use GPS to get to a new destination, but to turn it off on the way back or when going to familiar locations. You might even try to draw your own map from a "birds-eye view" perspective.

"We live in a society that's so fast paced that it encourages us to feel bad if we get lost," says Bohbot, fearing that reduced use of spatial strategies may lead to earlier onset of dementia. "What I say to people is that we can use GPS to explore the environment, but don't become dependent on it. (Developing) a cognitive map may take longer, but it’s worth the investment.”

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