By Jennifer Warner
WebMD Medical News
Reviewed By Louise Chang, MD
on Monday, November 14, 2005
Nov. 14, 2005 -- Regular walks in the park may keep your mind young as well as your body in shape.
A new study shows that a lifetime of moderate exercise, such as walking 30 minutes or a light 1-mile run per day, can fight the effects of aging in the brain.
Researchers found rats that had access to exercise, in the form of a running wheel, throughout their lifetime had healthier DNA and less evidence of damaged brain cells than rats that were sedentary all their lives.
"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," says researcher Thomas Foster, PhD, of the McKnight Brain Institute of the University of Florida, in a news release. "The results show that regular mild exercise can prevent oxidative damage. In people, that translates to a daily 30-minute walk or a light 1-mile run.
"It would be wonderful if we had a pill that contained all the benefits of exercise, but we don't," says Foster.
Exercising for Fun Keeps Brain Young
Researchers say oxidative damage in the brain is a natural consequence of aging and is thought to contribute to memory loss and other forms of age-related mental decline.
In the study, presented this week at the Society for Neuroscience's annual meeting in Washington, researchers compared the effects of moderate exercise on oxidative damage in the brains of rats that had lived to old age.
One group of rats had access to an exercise wheel throughout their lives, and the other group did not and led more sedentary lives.
After their death, researchers measured markers of oxidative damage in the animals' brains and found the more active rats had experienced less damage than the sedentary ones.
"The DNA for these animals after two years looked as if it were from their younger counterparts of only about 6 months of age," says Foster. "It shows a little bit of exercise may stimulate the body to fight stress that's normally occurring in the brain."
But experts say translating those results to humans may not be as simple.
"The difference between humans and rats is that it isn't as easy to get humans to exercise," Eric Klann, PhD, professor of molecular physiology and biophysics at the Baylor College of Medicine, says in the news release. "Put an exercise wheel in a rat cage and a rat will zoom around on that thing all the time, unless it's sleeping. But putting an exercise machine in your family room doesn't mean you're going to use it."
SOURCES: Society for Neuroscience's 35th annual meeting, Washington, Nov. 12-16, 2005. News release, University of Florida Health Science Center.
Much of the new research suggests that exercise positively affects the hippocampus, a sea-horse shaped brain structure that is vital for memory and learning.
- In one recent study, researchers found that adult mice doubled their number of new brain cells in the hippocampus when they had access to running wheels. The fact that the mammalian adult brain can increase its number of brain cells is surprising in itself. It was once thought that the brain stopped producing new brain cells early in its development. And presumably brain power dimmed as cells died over the years. But in the past decade, researchers have found definitive evidence that the brain continues to generate new brain cells throughout life, even in humans. Studies indicated that challenging environments, which included a number of components, such as pumped-up learning opportunities, social interactions and physical activities, were key to boosting the growth.
- In the new study, the scientists found that voluntary physical activity alone was enough to trigger a boost in brain cell proliferation. So far, the proliferation is seen only in relation to the running wheel. Swimming produced no change in mice and rats, but this may be because these rodents had pool access for only a brief stint per day. The runners had round-the-clock wheel access. It's also possible that rodents don't enjoy swimming and it causes a stress to their systems that counters any benefit. Researchers believe that rodents particularly enjoy the running wheel because they will voluntarily trot away on one if it's in their cage. Mice will log some 20,000 to 40,000 revolutions or four to six miles per day.
- In the next phase of the research, scientists are trying to map the biological steps that induce the brain cell proliferation in the runners. One participant in the growth phenomenon may be brain-derived neurotrophic factor, which supports the function and survival of brain cells. The factor increased in the hippocampus of rats that voluntarily exercised on running wheels, according to an earlier report.
- In addition, scientists are studying whether exercise alters the molecular mechanisms that are important for learning and memory. It seems likely since the cell research shows that changes occur in the brain's learning and memory center. In addition, past behavioral research on mice indicated that treadmill running improved certain learning and memory tasks. Even members of a family of mice that were poor learners improved their performances on the tasks. The exercise also prevented an age-related decline in mouse performance.
- Researchers also are finding biological evidence that exercise can help the brain on other fronts. For example, animal studies are determining that exercise prevents the negative effects of chronic stress on the brain at the molecular level and boosts the brain's biological battle against infection.
- Together the group of studies suggests that an active lifestyle, whether filled with exotic gym classes or simple jogs, plays an important role in maintaining the function of the brain. Furthermore, the research indicates that specialized exercise regimens may help repair damaged or aged brains. Scientists are currently investigating this possibility.
For more information please contact Leah Ariniello, Science Writer, Society for Neuroscience, 11 Dupont Circle, NW, Suite 500, Washington DC, 20036.
