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 Story's mother died of the disease in the
1970s.
So Stone, 53, watches her diet, and she works out several times a
week. She's cut out almost all caffeine; she works puzzles like
Sudoku and crosswords.
Her approach sounds like common sense. In fact, 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 also good for the
brain.
But will a healthy lifestyle help prevent Alzheimer's disease, or
at least delay its onset?
As the number of Alzheimer's cases in the U.S. continues to
climb, such questions have taken on an urgent feel. The Alzheimer's
diagnosis is now shared by 5.4 million Americans, 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." 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 definitively.
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, research on Alzheimer's -- unlike research on
other major killers, such as cancer and heart disease -- remains in
its infancy.
Today, scientists know that Alzheimer's begins killing brain
cells 10 years or longer before forgetfulness, confusion and other
early symptoms appear. By the time memory problems start, the
disease is already consuming the brain.
Prevention, or simply finding ways to keep symptoms at bay for
another decade into old age, would be a major breakthrough for older
adults.
A new UC San Francisco study -- using a sophisticated
mathematical model to analyze many years' worth of observational
data about the influence of lifestyle on Alzheimer's -- suggests
that about half the world's known cases of the disease could be
attributable to seven modifiable risk factors.
Lack of exercise could cause 21 percent of Alzheimer's in
America, 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.
As an independent panel appointed by the National Institutes of
Health to assess a broad range of research on the disease found last
year, the problem with connecting lifestyle risks and Alzheimer's is
this: Many studies find correlation, but none definitively proves
cause.
"Our response to that is, you can't," said Charles DeCarli,
director of the UC Davis Alzheimer's disease Center. "You can't tell
half your group, 'Don't treat your diabetes.' You can't tell half
your group, 'Don't treat your hypertension.'"
DeCarli's new research, published in this month's Neurology
medical journal, followed people in midlife who had diabetes, weight
problems or were smokers.
Brain scans taken at 50, then again at 60, found significant
changes in most participants' brain structure -- notably including
the structure of the hippocampus, the brain's memory center, one of
the first regions that Alzheimer's disease damages.
Again, it's a clue that people's behaviors earlier in life could
put them at increased risk of dementia as they grow older.
"We have accumulating evidence saying that lifestyle
modifications may help," said Dr. Laurie Ryan, program director for
Alzheimer's disease clinical trials at the National Institute on
Aging.
Researchers know that many people live energetic, involved lives
and eat right but still get dementia. But for many other people,
said Ryan, it's possible that healthy habits will help keep their
brain pathways nimble enough that they never exhibit cognitive
decline, even if they have other evidence of Alzheimer's pathology.
"If I can put off Alzheimer's for a few years, that's good,"
Stone said. "And if I can put off the inevitable long enough, maybe
I'll never get it."
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