Monday, August 15, 2011

Exercise, diet could delay onset of Alzheimer's disease

Virginia Stone is worried: Alzheimer's disease seems to run in her family. Her 80-year-old mother, Kazue Storey, was diagnosed seven years ago, and Storey's mother died of the disease in the 1970s.

So Stone, 53, watches her diet and she works out at zumba class several times a week. She's cut out almost all caffeine, except for one Diet Pepsi every week. She works puzzles including Sudoku and crosswords.

"If you take care of all these things, you can put off dementia longer," Stone said.

Her approach certainly sounds like common sense. Many Alzheimer's specialists tell their patients that what is good for the heart — a healthy weight, daily exercise, no smoking, lots of fruits and vegetables, a network of social connections — is good for the brain.

But is that true? Will a healthy lifestyle help prevent Alzheimer's disease or at least delay its onset? As the number of Alzheimer's cases in the United States continues to climb, such questions have taken on an urgent feel. The Alzheimer's diagnosis is shared by 5.4 million U.S. residents, and that number is expected to rise to 16 million by midcentury.

The Alzheimer's Association calls the illness "the defining disease of baby boomers" — many of whom, like Stone, are dealing with it in their parents' lives.

For them, it's crucial to know whether lifestyle changes will make a difference. But the answer, like so much related to Alzheimer's, is hard to pin down.

"Alzheimer's is a complicated condition," said Bill Fisher, Alzheimer's Association of Northern California chief executive officer. "The answers are also going to be complex."

Strictly speaking, experts say, the only known risk factor for Alzheimer's is old age. Marked by the death of brain tissue and the resulting erosion of memory and ability to function, the disease is the nation's sixth-leading cause of death and thought to be responsible for 80 percent of dementia cases.

There is no cure, although one medication, Aricept, has been found to delay symptoms in some patients for a year or two.

Unfortunately, as Fisher points out, research on Alzheimer's — unlike research on other major killers, such as cancer and heart disease — remains in its infancy.

In large part, that's because for most of the 20th century, doctors thought Alzheimer's only caused those rare cases of dementia occurring before age 65, while they diagnosed dementia in the elderly as a different disease, one that was thought to be a normal, if not inevitable, part of growing old.

Once researchers concluded in the 1980s that the pathologies of early and old age dementias were the same, the science could make progress.

Study suggests risk factors

Today, scientists know that Alzheimer's begins its steady march of killing brain cells 10 years or longer before forgetfulness, confusion and other early symptoms appear. By the time memory problems start, the disease is consuming the brain.

Prevention, or even finding ways to keep symptoms at bay for another decade into old age, would be a major breakthrough.

There are tantalizing hints that lifestyle changes really might help.

A University of California at San Francisco study — using a sophisticated mathematical model to analyze many years of observational data about the influence of lifestyle on Alzheimer's — suggests that about half the world's known cases could be attributable to seven modifiable risk factors.

Lack of exercise could cause 21 percent of Alzheimer's in the United States, and high blood pressure could cause 8 percent, the study theorizes, while low educational attainment and midlife obesity might each cause 7 percent. Diabetes could account for 3 percent.

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