UF study shows exercise may keep mind healthy 

November 20. 2005 6:01AM

"Use it or lose it" is the old maxim about brain power.

Now a new University of Florida study shows that light exercise may keep your brain in shape, as well as your muscles.

In the first study to show that lifelong exercise decreases cellular aging in the brain, scientists from the McKnight Brain Institute say that moderately active rats have healthier DNA and more robust brain cells than their less active counterparts.

They're hoping the same is true of their human counterparts.

"It would be wonderful if we had a pill that contained all the benefits of exercise, but we don't," said Thomas Foster, the McKnight chair for brain research in memory loss at the College of Medicine. "For this study, animals were not forced to run; they did it because it was entertaining, the same as a pet hamster on a running wheel. The results show that regular mild exercise can prevent oxidative damage."

Foster said that in people, that formula translates to a daily 30-minute walk or a light one-mile run.

Of course, it's one thing to get a rat to run laps in an exercise wheel. But putting an exercise bicycle in front of the television set won't guarantee that anyone in the family will use it.

Scientists believe that oxidative damage in the brain is a natural consequence of aging and a contributor to memory loss. It has also been implicated in the loss of brain cells associated with Alzheimer's or Parkinson's disease.

Oxidative damage can occur when molecules of oxygen gain electrons and become free radicals. The free radicals regain their balance by giving electrons to their neighbors. Most of the time the body routinely handles these renegades, but sometimes not before extensive damage occurs in the cell.

Working with Christiaan Leeuwenburgh, associate professor of aging and geriatric research at UF's Institute on Aging, Foster looked at groups of rats that had lived to old age. Some were more sedentary, while others had access to an exercise wheel.

At the end of the experiment, scientists examined chemical compounds in 41 tissue samples taken from a part of the brain important for balance and movement.

The more active rats were found to have fewer by-products of oxidative stress in their brains. Fats known as lipids that help stabilize cell membranes, and DNA, the molecule that contains our genetic blueprint, both better withstood the rigors of time.

"The DNA for these animals after two years looked as if it were from their younger counterparts that were only about 6 months of age," Foster said. "It shows a little bit of exercise may stimulate the body to fight stress that's normally occurring in the brain."

Damage to DNA causes cell mutations and cell death. Finding ways to preserve it may help prevent age-related memory loss and defend against deterioration of balance and motor function - both important health goals as the U.S. population continues to age.

The UF group's research findings were presented this month at the Society for Neuroscience's 35th annual meeting in Washington, D.C.

"By age 50 almost everyone has mild memory deficits," Foster said. "We forget where we put the keys or jumble the names of our kids. If these losses increase, then we run into problems. We want to prevent that."