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Scientists project that some 13.2 million older Americans will have Alzheimer's
disease (AD) by 2050 unless new ways are found to prevent or treat
the disease. According to these latest estimates of the current and
future prevalence of AD, reported by Denis A. Evans, M.D., and colleagues
of Rush-Presbyterian-St. Luke's Medical Center in Chicago, the numbers
of older people with AD -- now at 4.5 million - will grow dramatically
as the population ages. The most notable increases will be among people
age 85 and older, when by mid-century 8 million people in that age
group may have the disease.
The projections appear in the August 2003 issue of the Archives of Neurology. "These updated estimates from Evans and
his group underscore the challenge that we face in the fight against
AD," says Marcelle Morrison-Bogorad, Ph.D., NIA Associate Director
for the Neuroscience and Neuropsychology of Aging Program, which funded
the research. "But I am also optimistic that current research
will lead to strategies for intervention early in the disease so that
we can keep these projections from becoming a reality."
The estimates were derived from a study of the incidence (number of
new cases of AD per year) over 4 years among 3,913 people 65 and older
in Chicago. The researchers then calculated the national prevalence
of AD (the number of people at any particular time who have the disease)
using population projections from the Census and death rates from
the National Center for Health Statistics. Their estimates, based
on Census Bureau "middle series" population projections,
are:
Number of People with AD, by Age Group
(in millions)
|
Year
|
Age
65-74
|
Age
75-84
|
Age
85+
|
Total
|
|
2000
|
0.3
|
2.4
|
1.8
|
4.5
|
|
2010
|
0.3
|
2.4
|
2.4
|
5.1
|
|
2020
|
0.3
|
2.6
|
2.8
|
5.7
|
|
2030
|
0.5
|
3.8
|
3.5
|
7.7
|
|
2040
|
0.4
|
5.0
|
5.6
|
11.0
|
|
2050
|
0.4
|
4.8
|
8.0
|
13.2
|
In 2000,
7 percent of those with AD were age 65-74, 53 percent age 75-84, and
40 percent age 85 and older. By 2050, it is projected that 60 percent
of people with AD will be 85 and older.
In 2000, among people age 65-74, 17 percent of the cases of AD were
classified as severe, compared with 20 percent severe among people
75-84 and 28 percent severe at age 85 or older.
"Declines in death rates after age 65 mean that more people will
survive to the oldest ages, where risk of AD is greatest," notes
Evans. "These numbers validate the current thinking that we must
do what we can as early as possible in the disease process, prior
to advanced age, if we are to head off these very high rates of AD
in the future."
Over a decade ago, Evans and colleagues estimated the national prevalence
of AD, based on an East Boston, MA, population study. The new estimates
are similar to those earlier findings.
The
updated findings were reported by Evans, Liesi E. Hebert, Julia L.
Bienias, and David A. Bennett of Rush and by Paul A. Scherr of the
Centers for Disease Control and Prevention. The NIA, along with funding
this study, also supports the Rush Alzheimer's Disease Center. The
Alzheimer's Association also provided funding for the prevalence study.
AD is an irreversible disorder of the brain, robbing those who have
it of memory, and eventually, overall mental and physical function,
leading to death. For more information on such research, as well as
on biological, epidemiological, clinical, and social and behavioral
research on AD, two new publications are available from the NIA: 2001-2002
Alzheimer's Disease Progress Report and Alzheimer's
Disease: Unraveling the Mystery, which includes a CD-ROM animation
of what happens to the brain in AD. These publications may be viewed
at NIA's AD-dedicated Web site www.alzheimers.org,
the Institute's Alzheimer's Disease Education and Referral (ADEAR)
Center or ordered free by calling ADEAR at 1-800-438-4380.
For general information about aging and health, including materials
on exercise specifically aimed at people 50 and older, visit the NIA
Web site at www.nia.nih.gov or
ask for a publications list by calling 1-800-222-2225.
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