- WASHINGTON (Reuters) - The number of Alzheimer's cases in the United States
will more than triple over the next 50 years, although drugs that could
in the future delay the onset of the brain-destroying disease would help
significantly, researchers said Tuesday. Ron Brookmeyer and colleagues
at the Johns Hopkins University School of Public Health examined several
studies linking Alzheimer's to age and found that about 2.3 million Americans
currently suffer from the disease. Other estimates have ranged to above
four million. About 4 percent of 75-year-olds, 8.5 percent of 80-year-olds
and 28.5 percent of 90-year-olds suffer from Alzheimer's, which is incurable
and always fatal, Brookmeyer's team found. ``It is estimated that there
are approximately 360,000 new cases of Alzheimer's disease each year,''
they wrote in the American Journal of Public Health. The researchers, who
specialize in such statistics, compared those rates to projections for
the U.S. population and found cases would more than triple. ``Within the
next 50 years, the prevalence could be expected to rise by a factor of
3.7, to 8.64 million,'' they wrote. ``The annual number of new cases could
be expected to rise more than three-fold, from 360,000 cases in 1997 to
1.14 million new cases in 2047.'' But they said treatment that delayed
the onset of disease would greatly reduce that impact. Delaying onset by
one year would result in 210,000 fewer cases 10 years later and 770,000
fewer cases 50 years later. There are no drugs on the market that really
do that, but companies are working to develop them. Current drugs can help
symptoms. Two drugs are approved in the United States for use against Alzheimer's.
Aricept, made by Japan's Eisai Co. Ltd. and distributed by Pfizer, can
help reduce memory loss but eventually stops working. Warner-Lambert's
Tacrine (Cognex) can slow the progression of the disease but not by very
much. A third drug, metrifonate, which is made by Bayer, is up for approval
by the U.S. Food and Drug Administration (FDA). Ginkgo, a tree extract,
may also help sharpen the memory in Alzheimer's patients. Another problem
is diagnosing Alzheimer's. Most experts agree the only real way to diagnose
Alzheimer's is with a brain biopsy -- which is done after death. ``There
has been continuing debate about whether Alzheimer's disease incidence
rates continue to rise at the oldest ages, or if they eventually plateau
or even decline,'' Brookmeyer said in a statement. ``The data in this study
suggested that the risk of Alzheimer's disease continues to rise at least
through age 90 but there is little reliable data about risk beyond 90.''
Alzheimer's starts with simple memory loss and advances to confusion, severe
memory loss and physical deterioration as more brain cells are destroyed.
There is a genetic factor, but outside influences are also important. Doctors
are trying to learn what those might be -- from what food people eat, to
viral or bacterial infections.