Three times a week, 80-year-old Sue Lewis puts on her tennis shoes and goes for a brisk walk around her neighborhood running track. But she doesn't just walk around it once or twice. Ten laps doesn't stop her -- and after 15 laps, you can bet she's still moving. In fact, Lewis has been known to walk around the track as many as 46 times a day. "I walk pretty fast. My cousin has a hard time keeping up with me," she says.
If she's not on the track, you might find Lewis on the treadmill or walking up mountains and across the grass at her family farm in Georgia. Her "keep on moving" motto isn't just keeping her body in great shape, however. Researchers say her brain gets a workout too. Last spring, investigators from the University of California, San Francisco (UCSF), told a conference of nerve specialists that walking may help older women keep their brains young.
"Women who walk regularly are less likely to experience the memory loss and other declines in mental function that can come with aging," explains study author and neurologist Kristine Yaffe, MD.
Indeed, Lewis is as sharp as she is quick on her feet.
"My memory is great," she says. "I'm sharp as a tack, even though I do forget where I put my glasses from time to time."
Flexing Your Mental Muscle
For the study, UCSF researchers tested the thinking power of about 6,000 women aged 65 and older. The women were given a mental exam at the start of the study and then again six to eight years later.
Yaffe and her colleagues found that the women who walked the least -- less than a half-mile a week -- were the most likely to develop mental decline. Nearly a fourth showed significant declines in their test scores, compared to only 17% of women in the most active group.
"It doesn't seem like a big difference, but it really is," says Yaffe.
Physical activity was charted by measuring the number of blocks the women walked per week and also by the total calories they burned in recreation, walking, and climbing stairs. The most active women walked about 18 miles a week, or 2.5 miles a day.
If 18 miles a week classifies you as physically active, then 77-year-old Lura Roehl just might be superwoman. The Washington, DC, native walks three times a day, every day, with her 80-year-old husband, Charles. Together they clock 46 miles a week.
Roehl likes the idea that her everyday routine may be keeping her brain healthy. Like Lewis, this power-walker says her memory is as sharp as ever and that's how she'd like to keep it.
You don't have to wait until retirement to reap the benefits of walking, though. Experts say the more you walk, the better -- and the earlier you start, the better. At age 38, Jane Niziol still has quite a few years left before she'll start seeing any senior citizen discounts or signs of age-related memory loss. But she's not waiting until old age to start her workouts. She walks six miles every evening after work. "Walking makes me feel great," says Niziol. "It's hard thinking about things like heart disease or Alzheimer's at my age, but I want to make absolutely certain I'm still moving in my golden years. That's why I'm moving now."
Doctors have long touted the benefits of exercise for preventing things like heart disease and diabetes, but until now, few have suggested that the same rule of thumb could be applied to degenerative brain disorders like Alzheimer's.
"Science has definitely lagged behind in terms of trying to find those things that we can do physically to keep the brain healthy," says Danielle Gray, a neuroscientist at Emory University in Atlanta.
Warding Off Dementia
The most common cause of cognitive decline and dementia is Alzheimer's disease. It's a progressive disease that leads to the loss of mental abilities like memory and learning. Today, about 4 million people in the U.S. suffer from this disorder, but that number is expected to skyrocket over the next few decades.
"It's predicted that in the year 2050, there will be 14 million people with Alzheimer's. That's an astronomical leap," says Gray. "So you can imagine -- that's why we are now poised to try and do something about this illness."
Gray is a firm believer that physical activity, in addition to a proper diet, can help ward off the dementia so commonly associated with aging. The exact mechanisms are not yet understood, but Gray says one theory is that aerobic exercise boosts mental performance and short-term memory by increasing blood flow -- and therefore oxygen -- to the brain.
Yaffe is planning studies to examine the issue further. She says that while there's been a lot of effort recently to identify medications to prevent Alzheimer's, few have explored non-drug approaches.
"We know that exercise is good for the body. Now there's a lot of interesting data to support that it can also be good for the brain," says Yaffe. "It would be super to find something other than medications that might help prevent cognitive decline."