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How Exercise Affects the Brain and Improves Memory

Two senior black women exercising together
Walking improves brain blood flow, clears brain toxins.
David Walters

For years, doctors have recommended exercise as one of the best ways to keep our brains healthy as we age. Now new research finds that regular sustained exercise may be able to slow or even reverse the biological changes that cause dementia. What’s more, exercise may even be an effective treatment for those with Alzheimer’s disease and vascular dementia.

The findings, presented this week at the Alzheimer’s Association International Conference in Washington, D.C., have important implications for an aging population at risk for developing memory and thinking problems as they age.

Clearing toxic tau

In one study, 71 sedentary men and women, average ages 55 to 90, with mild cognitive impairment — memory loss, which is often a precursor to Alzheimer’s disease — and prediabetes exercised at a YMCA for 45 minutes four times a week over six months. Because the study subjects were all sedentary, the trainers worked with the participants for six weeks, to gradually increase their fitness levels until they could get their hearts pumping to 75 to 85 percent of their maximum heart rate for half an hour. A control group did supervised stretching exercises at the YMCA four times a week.

Lead author Laura Baker, and her colleagues at Wake Forest School of Medicine in Winston-Salem, North Carolina, found that exercise not only improved thinking skills in those with memory problems but also reduced levels of toxic tau protein in the brain. In addition, the vigorous-exercise group experienced improved blood flow to areas of the brain that are usually restricted in those with memory loss. The stretching group had no improvements in blood flow or tau protein levels.

Notably, the exercise group improved from their original scores by 15 percent on three tests of executive function, which measures the ability to plan and organize thoughts. Executive function is often one of the first casualties of early Alzheimer’s disease. Compared with the stretching group, which continued to decline, the exercise group performed an average of 80 percent better on the tests for executive function. Plus, blood pressure and triglyceride levels dropped in the vigorous-exercise group, Baker said.

“If there was a new drug on the market that would improve cognitive function by 15 percent, increase blood flow in critical areas for thinking in the brain, reduce toxic proteins in the brain associated with Alzheimer’s disease and improve overall health status — with no side effects — who wouldn’t take this drug?” Baker said. “The company would make a fortune.”

Exercise as a treatment for Alzheimer’s

So exercise can improve memory, function and brain biology in those with serious memory loss, but could it also help those who already have Alzheimer’s disease? Researchers in Denmark decided to find out. They assigned 200 patients to either an exercise group or a control group. The exercise group did aerobic activity for 60 minutes three times a week for four months. The researchers found that the group as a whole didn’t experience improved memory and thinking skills, but a group that exercised more vigorously — 70 percent of maximum heart rate — did see improvement in mental speed and attention.

The exercise group also had less anxiety, irritability and depression than they did before the study, while the control group worsened. These symptoms are important because agitation and other disturbing behaviors are often some of the main reasons Alzheimer’s patients end up in nursing homes.

“We were able to improve symptoms of Alzheimer’s disease with physical exercise,” said Kristian Steen Frederiksen, one of the study’s authors. “This gives hope that exercise is an important adjunct to the medical treatment of Alzheimer’s disease.”

Walking for better brain blood flow

In a third study presented at the Alzheimer’s conference, Teresa Liu-Ambrose of the University of British Columbia presented research on exercise as therapy for people who have vascular cognitive impairment, a common form of memory loss caused by lack of blood flow to the brain that results in ministrokes.

In her study, 30 people with vascular dementia exercised outdoors for 40 minutes three times a week with a 10- to 15-minute warm-up and cooldown. Another 30 men and women took cooking and nutrition classes. The researchers found that, at six months, the walking group improved on memory tests whereas the nutrition group got slightly worse.

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Liu-Ambrose said she recommends exercising two to three times a week and combining walking or other movement with some kind of resistance training, but that doesn’t necessarily mean pumping iron in a gym. Squats, doing biceps curls with soup cans — every bit helps.

“I want to emphasize the message that something is better than nothing,” said Liu-Ambrose. “Starting is better than remaining sedentary, even if you start late in life. It’s like retirement planning. Never starting is the worst case. The earlier you start, the better off you will be, but it’s never too late to start.”

Photo: kali9/iStock

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