WEDNESDAY, April 25, 2007 (HealthDay News) -- New research suggests more evidence of yet another benefit of regular exercise: It could keep Parkinson's disease at bay.
The study doesn't conclusively link exercise to better brain health, but scientists think the connection could be more than a fluke.
"The people who seemed to have a lower risk of disease were engaging in moderate to vigorous activity for two to three hours a week," said study leader Evan Thacker, a research assistant at the Harvard School of Public Health.
Parkinson's disease is a movement disorder that worsens over time and causes a variety of symptoms, including disruptions in movement, as neurons in the brain deteriorate. The cause of the disease is not known, and there is no cure, but drug therapy and surgery can help manage symptoms, according to the Parkinson' Disease Foundation.
An estimated 1.5 million Americans have the disease, and 60,000 new cases are diagnosed each year, according to the foundation. Among famous people who have the condition are the actor Michael J. Fox and former U.S. Attorney General Janet Reno.
In what Thacker called the largest research project of its kind, researchers looked at the results of a federal cancer study that followed 63,348 men and 79,977 women from 1992 to 2001. Of the participants -- with an average age of 63 -- 413 of them developed Parkinson's disease.
The researchers looked at exercise levels and tried to determine if they affected the rate of Parkinson's disease after adjusting the numbers to reflect the possible influence of factors such as age, gender and smoking.
People who exercised more than 75 percent of their fellow study participants were 20 percent less likely to develop Parkinson's, compared to those who didn't exercise. The risk of the disease was 40 percent lower in those who took part in the highest levels of moderate to vigorous activity, defined as exercise such as jogging, lap swimming, tennis and bicycling, the study found.
However, there's one caveat -- the researchers found no indication that physical activity at age 40 affected the risk of developing Parkinson's.
The results were expected to be reported Monday at the American Academy of Neurology annual meeting, in Boston. As is often the case with research presented at conferences, the study has not been published in a medical journal or gone through the review process that journals require.
A previous study suggested a link between exercise and Parkinson's in men, but not in women, Thacker said. The new findings show both genders may benefit.
Still, he cautioned that his study isn't "the final word."
"We can't prove there was some other factor that caused people to be different," he said. "We can just do the best we can.
Thacker said it's still not clear why exercise might influence the development of Parkinson's. One possibility could be that exercise might affect chemicals in the blood that play a role in the development of the disease, he said.
Researchers at the University of Southern California have found evidence suggesting that exercise changes the way neurons release dopamine -- a crucial brain booster -- in mice, said Michael Jakowec, an assistant professor of neurology at the school.
Disruptions in dopamine production have been linked to Parkinson's.
According to Jakowec, both animal studies and brain imaging in humans will help scientists understand the effects of exercise on the brain.
More information
To learn more, visit the Parkinson's Disease Foundation.
