By Brenda Goodman, MA
WebMD Health News
Reviewed by Michael W. Smith, MD
Aug. 7, 2015 -- Scientists have a message for anyone who's worried about memory loss -- move, a lot.
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Researchers have known for some time that exercise is good for aging brains. The latest studies, though, are adding some finer points to that message: While exercise appears to work best before memory fades, it also benefits people who've already gotten dementia. And it seems to help not just with Alzheimer's disease, but also with vascular dementia, a kind of memory loss that's caused by "silent" strokes in the brain.
Three studies presented at the recent meeting of the Alzheimer's Association in Washington D.C. detailed the effects. Exercise lowered levels of toxic tau proteins and increased blood flow in the brains of people with early memory changes that put them at risk for dementia. Four months of intense exercise improved symptoms like anxiety, irritability, and depression in people with Alzheimer's, though it didn't help their memories. But 6 months of exercise did improve memory and thinking in people diagnosed with vascular dementia.
Experts say these are important gains for patients who have few effective treatments.
"No currently approved medication can rival these effects," says researcher Laura Baker, PhD, an associate professor of gerontology and geriatric medicine at the Wake Forest School of Medicine.
The Powerful Protection of Exercise
"Exercise is, right now, the most powerful effect in terms of prevention of Alzheimer's disease," says Stephen Rao, PhD, the director of the Schey Center for Cognitive Neuroimaging at the Cleveland Clinic.
"I'm sure a drug is going to come along that will also work in terms of prevention. But right now, the best thing you can do to prevent Alzheimer's is to get people on a treadmill or walking," he says.
Rao has been studying older adults who carry a gene that greatly raises their risk for Alzheimer's disease. About 1 in 5 Americans carry at least one copy of this gene, called APOE4, and it boosts their risk of getting the disease from 3- to 15-fold, depending on whether they have one or two copies of it. When Rao's team started the studies, his volunteers showed no signs of memory or thinking troubles.
When people with APOE4 genes exercised regularly, their brains stayed healthy. They aged more like people with no genetic risk. When they sat too much, though, Rao could see key brain structures shrinking over time on imaging scans. They also did worse on written tests of memory and thinking.
Exercisers, on the other hand, have brains that are more connected. They have more white matter, a kind of tissue that's thought to act like electrical wiring, keeping all the parts of the brain talking to each other. And their brains don't appear to shrink, or lose volume, over time.
To Rao, these results are a no-brainer. "If you're at risk for Alzheimer's because you have a family history, because you have this genetic risk factor, you should be working really, really hard to exercise. And that should start at least in middle age."
A High Dose for Brain Health
That's the good news. The not-so-great news is that studies are showing that it takes a pretty big commitment to get this protection -- at least 3 hours, or 180 minutes, of vigorous physical activity each week. That's significantly more than the 150 minutes a week that government guidelines recommend.
Vigorous physical activity is any exercise that makes you pant and sweat. And it requires people to get their heart pumping at 70% to 80% of their age-related maximum heart rate. For someone who's 65 years old, that's somewhere between 109 and 124 beats per minute.
Experts say in order to see the brain benefits, it's really important to hit the right dose of physical activity.
"I talk about exercise in the same kind of terminology you might use for a drug. Because if we can't get the right dose of medicine, we're not going to see the effects," Baker says.
Baker studies adults who have a condition that greatly raises their risk of Alzheimer's disease. They've been diagnosed with mild cognitive impairment, or MCI, which means they have more memory problems than would be expected for their age, but those troubles have not yet impacted their daily life.
They can still live independently and feed, dress, and bathe themselves. But it usually takes a lot more effort to do things like grocery shop or balance the checkbook. People with mild cognitive impairment -- which affects an estimated 10% to 15% of adults over the age of 65 -- typically rely heavily on notes and calendars to get through the day.
Not everyone with MCI will progress to Alzheimer's disease, but many do.
Baker has randomly assigned people with MCI to one of two groups -- a group that exercised vigorously for 6 months or one that stretched on a regular basis. In her studies, exercisers are supervised by a trainer and are told to shoot for 3 to 4 hours of exercise at 75% to 85% of their maximum heart rate each week. The stretching group met for the same amount of time, but they kept their heart rate low while they limbered up.
After 6 months, the exercisers improved on tests of thinking and memory, and the effects were larger for women than for men.
In more recent studies, she has looked at the combined effects of exercise and diet and found that exercise boosts the benefits of a healthy diet, lowering levels of brain-clogging bits of beta amyloid proteins in spinal fluid.
Her latest results show that people with MCI who hit this high dose of exercise for at least 6 months also had less toxic tau protein and better blood flow compared to the stretching group.
Baker says she knows this is a lot of exercise, especially for people who aren't used to it. And it's hard for most people to make big lifestyle changes like this. She's doing further studies to see if the dose has to be this intense, or if people could get away with a more leisurely pace or less rigorous schedule.
"My big caution is start very slowly," Baker says, "Give yourself 6 weeks to get up to an intensity that is really effortful."
SOURCES: Stephen Rao, PhD, director, The Schey Center for Cognitive Neuroimaging, The Cleveland Clinic, Cleveland, Ohio. Laura Baker, PhD, associate professor, Department of Gerontology and Geriatric Medicine, The Wake Forest School of Medicine, Winston-Salem, N.C. Alzheimer's Association International Conference 2015, Washington D.C.
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