MARCH 2007

TO PARAPHRASE a popular public-service commercial, This is your brain… this is your brain on exercise. But in this case, the message is hopeful instead of scary: As little as three hours a week of brisk walking can actually reverse the brain deterioration brought on by aging. According to new research at the University of Illinois, aerobic exercise can increase the brain’s amount of “gray matter”—neurons —as well as its “white matter,” the connections between neurons, in older adults.

“Ten years ago you would never have expected to see this in older adults,” said psychology and neuroscience professor Arthur F. Kramer, PhD, lead author of the study, which was published in the Journal of Gerontology: Medical Sciences. Until recently it was believed that age-related brain shrinkage and cognitive decline were inevitable, and that the brain can’t grow new neurons. This view has changed with demonstrations in animals that older brains can show positive changes in response to exercise, diet, social and environmental stimulation, Kramer said.

This is the first study of older human subjects to find that exercise can actually reverse the brain shrinkage and natural wear and tear that starts in mid-life.

The research involved 59 healthy but sedentary volunteers, ages 60-79, who participated in a six-month randomized clinical trial, meeting three times a week. Half did aerobic exercises such as brisk walking, while a control group did only non-aerobic stretching and toning exercises. Researchers compared high-resolution magnetic resonance imaging (MRI) brain scans before and at the end of the exercise program.

Mental “exercises” can also help combat cognitive decline with aging… see page 6

After six months, those in the aerobic exercise group showed significant increases in brain volume, while those in the control group did not. The prefrontal and temporal cortices of the brain—areas responsible for memory and information-processing that are especially prone to age-related deterioration —showed the greatest gains from aerobic exercise.

Although the study group was small, the findings align with other research, including the researchers’ 2003 cross-sectional study, also in the Journal of Gerontology, showing a correlation between lack of physical fitness and brain tissue loss in older adults. The latest study did not address possible effects of exercise on diseases such as Alzheimer’s, nor did it look at whether more strenuous exercise could confer greater benefits.

“Moderate levels of exercise—in particular, walking—are relatively easy to do,” Kramer noted, “and may result in increased cognitive flexibility and the ability to lead independent lives for longer periods of time.”

In this case, people who had been couch potatoes started with 15 minutes of exercise, built it up to 45 minutes and showed improvements in brain volume as well as physical fitness. “You don’t have to be a marathon runner—most people walk,” Kramer said. Swimming, biking and walking are all ways that people can get these anti-aging brain benefits, he added.

For “9 Easy Ways to Add Exercise to Every Day,” see the August 2006 Healthletter.