MONDAY, May 7 (HealthDay News) -- If you're looking for a way to keep dementia at bay, a new study suggests you can do so by developing a firm purpose in life.

The findings don't prove that having a purpose will make a difference, and it's possible that the researchers missed another important factor that's at play. Still, the study found that people who had more purpose -- as defined by the researchers -- seemed to be less affected by the brain-clogging gunk that's considered to be a cause of Alzheimer's disease.

"Somehow, having a purpose allows people to cope with the physical signs of Alzheimer's disease," said Patricia Boyle, an associate professor at the Rush Alzheimer's Disease Center at the Rush University Medical Center in Chicago.

Boyle and colleagues looked at tests given to 246 older people who later died and underwent autopsies that explored the state of their brains.

The researchers defined a purpose in life as "the tendency to find meaning from life experience, to be intentional and focused," Boyle said. "It's an indicator of well-being, that life is good and you are contributing to your life, you're making decisions."

To determine purpose in life, the researchers analyzed answers from a 10-item psychological test.

Among those who had a lot of brain gunk -- known as plaques and tangles -- the ones who had greater purpose in life appeared to be less affected by a decline in their mental (or "cognitive") powers. "The rate of cognitive decline was about 30 percent slower for someone with greater purpose in life, compared to someone with less purpose," Boyle said.

The researchers found that they were able to link a higher sense of purpose to better brain health even when they adjusted their statistics so they wouldn't be thrown off by high or low numbers of people with illness, signs of depression and other factors.

It's still not clear that purpose in life has anything to do with mental powers in old age. But if there is a connection, it may have something to do with the brain's capacity, said Dr. James Burke, director of the Memory Disorders Clinic at Duke University Medical Center.

Similarly, people who have more education seem to be better able to tolerate brain-clogging plaques and tangles without having as many cognitive problems, Burke said. "My own analogy is that if a city has more roads, it can tolerate more blocked roads while still allowing you to get to your destination. This is commonly used as the explanation, but difficult to prove."

The study is published in the May issue of the Archives of General Psychiatry.

In other Alzheimer's disease news, a small new study indicates that deep brain stimulation -- a treatment being tested to treat mental problems -- seems to help the brain work more efficiently in people who appear to have a mild form of the disease. (The disease can't be conclusively diagnosed until after death.)

The researchers, Gwenn Smith of the Johns Hopkins University School of Medicine and colleagues, examined four men and one woman who underwent the treatment for a year.

In deep brain stimulation, the brain is zapped with an electronic pulse that comes from a pacemaker-like device implanted in the chest.

The study, which was published online May 7 in the Archives of Neurology, was very small and "a very early look" at a new kind of treatment, noted Burke, who was not involved in the research. More research is needed, he added.

More information

For more about Alzheimer's disease, visit the U.S. National Library of Medicine.