Study: Exercise Keeps the Brain Sharp

Jan. 30 -- New research shows that physical fitness can actually affect the structure of the human brain, and exercise may be our best friend when it comes to keeping the old noggin tuned up while we age.

We've been told for years that staying fit helps fight off the decline in cognition due to aging, and that's common sense because the brain, after all, is part of the body. But for the first time scientists have literally looked inside the human brain and found that people who exercise regularly maintain a physiological advantage over couch potatoes.

To put it simply, their brains don't shrink as much.

Keeping Your Grays and Whites

The researchers used high-resolution magnetic resonance imaging to study the brains of 55 volunteers between the ages of 56 and 79. They found that those who were physically fit had lost far less of their brain's gray and white matter than those who got very little exercise.

"People who are most fit showed the largest benefit," says psychologist Arthur F. Kramer of the University of Illinois at Urbana-Champaign. "They showed the least amount of reduction in brain volume."

Gray matter is home to the neurons that are so important to learning and memory. White matter is sort of the brain's Internet, with fibers that send signals throughout the brain. Scientists have known for years that these tissues begin to shrink at about the age of 30 in a pattern that closely matches declines in cognitive performances, says Kramer, leader of the research team.

But the new research shows that the decline can be minimized by physical exercise, because the fitter participants had more gray and white matter than those who exercised less.

Furthermore, the areas that showed the most benefit are the same areas associated with mental decline due to aging, such as short-term memory loss.

The researchers found far more gray and white matter in the frontal, temporal and parietal cortexes among the physically fit participants.

That's particularly significant because of the role each of those areas plays in the cognitive processes.