July 14 (Bloomberg) -- People with Alzheimer's who exercise regularly had less brain damage, a finding researchers said may one day lead to development of a treatment to slow the disease.

Physically fit patients with mild cognitive impairment had less brain shrinkage than those who weren't so well conditioned, according to a study released today in the journal Neurology. Brain function declines as the disease progressively kills nerve cells, causing the organ to lose volume, researchers said.

Previous studies showed exercise improves thinking and memory, in people with normal brain activity, by boosting blood flow and elevating growth hormones, the scientists said. The new findings extend this connection to people with Alzheimer's. Understanding how exercise affects the brain could help scientists find a new target for drugs, the researchers said.

``Until now, there was no data to suggest people with Alzheimer's may benefit from regular exercise,'' said the study's lead author, Jeffrey Burns, in a telephone interview on July 11.

While the study found that patients with better cardiovascular health were more likely to have greater brain volumes, further research is needed to determine if exercise prevents brain loss, according to the researchers. Another explanation for the findings may be that the advancement of Alzheimer's reduces patients' ability to exercise, the authors wrote.

The five drugs approved in the U.S. to treat Alzheimer's mask symptoms for 6 to 12 months at most, according to the Alzheimer's Association, an advocacy group based in Chicago. While deaths from heart disease, breast cancer and stroke declined from 2000 to 2005, fatalities attributed to Alzheimer's increased 44.7 percent.

The National Institute on Aging and the National Institute on Neurological Disorders and Stroke funded the new research, which used magnetic scans to measure brain size in Alzheimer's patients.

To contact the reporter on this story: Cristina Alesci in New York at calesci@bloomberg.net

Last Updated: July 14, 2008 17:20 EDT