Can Alzheimer’s Be Prevented? Exercise Offers Some Hope
By Robert A. Barnett  
Published 2/26/2013 
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Exercise is a key to a healthy heart — and brain. In fact, it may play a particularly powerful role in helping to prevent Alzheimer’s disease in people at high risk.

“There is accumulating animal and human evidence that exercise is not only good for the body but also for the mind, specifically the brain,” says Stephen M. Rao, Ph.D., director of the Schey Center for Cognitive Neuroimaging and a professor at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. It’s part of our growing recognition that a heart-healthy lifestyle may also help ward against Alzheimer’s and other forms of dementia.

A Nasty Gene Neutralized by Exercise

One in four people carries a gene that causes a cholesterol abnormality — and triples their risk of developing Alzheimer’s disease. This gene spurs production of a protein called ApoE4. People with ApoE4 are more likely to experience buildup of amyloid in their brains, and these collections, visible on a CT scan, are a key marker for Alzheimer’s disease. “In brain imaging studies, people with this genetic variation tend to show cognitive decline as quickly as one and a half years later after the baseline scan,” says Dr. Rao. 

But not everyone with the gene gets the disease. Regular exercisers don’t show the brain changes associated with Alzheimer’s. Their brain imaging studies look like those of people without ApoE4. Their brains show a pattern, explains Dr. Rao, which is “protective against future cognitive declines.”

Exercise Prevents Progression of Alzheimer’s

Exercise appeared to prevent the negative effects associated with the risky gene (we don’t know if it’s overexpression or underexpression that’s the problem). Population studies add further support. In a three-year study of 560 Dutch men with the ApoE4 abnormality, those who were active for less than an hour a day were four times more likely to experience cognitive decline compared with those who were active for more than an hour a day. Another study, over 21 years, found that older adults (ages 65 to 79) with ApoE4 who broke a sweat and increased breathing rate for 20 to 30 minutes, two or three days a week, decreased their likelihood of developing Alzheimer’s by one-third in comparison to a more sedentary group. Exercise has also been shown to help slow rates of cognitive decline in people with early signs of dementia.

Though not all the results are in, and researchers cannot specify the precise beneficial amount of protective exercise, it’s clear that the same exercise that protects our hearts also protects our brains.

Move Your Body, Benefit Your Brain

Exercise has many other brain benefits too, including for people not at high risk of developing Alzheimer’s. At all ages, physical activity and fitness is associated with more “gray matter” — including in the hippocampus, the part of the brain that forms memory. Exercise stimulates the creation of new neurons and new blood vessels, and it increases delivery of oxygen to brain tissue. A yearlong study of elderly individuals showed that those who did not exercise regularly lost hippocampus size. The hippocampi of those who exercised remained the same size or even increased.

“In standardized cognitive tests, the brains of older individuals who exercise regularly look less atrophied,” says Dr. Rao. “Whether exercise actually prevents, or merely slows down the rate of, Alzheimer’s disease is still a question. But there is an increasing body of scientific literature that shows that exercise is very important for the brain.”

Exercise also helps control weight, reduce the risk of diabetes, raise good HDL cholesterol levels and lower high blood pressure. Each of these is a risk factor for Alzheimer’s disease. Indeed, people with prediabetes or newly diagnosed type 2 diabetes who embarked on an aerobic exercise program showed improved cognition compared to a control group who were encouraged simply to stretch.

The Brain-Health Exercise Prescription

So what’s the exercise prescription for brain health? For now, the best advice we can give is to follow these recommendations for heart health. No matter what type of exercise you’re doing:

  • Seek an intensity level that increases your heart rate so that your breathing is a bit labored but you can still carry on a conversation.
  • If you’re new to exercise, aim for 30 minutes three times a week, working up to at least 30 to 45 minutes a day five or more days a week.
  • If you’re currently sedentary, start slowly, building up gradually over a month or more.
  • Don’t have time for 30 minutes at a time? Break it up — three 10-minute brisk walks or two 15-minute jaunts work just fine too.
  • Buy a pedometer and track your steps. If you get 10,000 steps a day, you’re doing great. Pedometers can also help you stay motivated.
  • If you have risk factors for cardiovascular disease, talk with your doctor before you start your exercise program. You’ll want to be sure it’s safe.

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