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Alzheimer's Disease Fact Sheet
Alzheimer's disease (AD) is the most common cause of dementia in older people.
A dementia is a medical condition that disrupts the way the brain works.
AD affects the parts of the brain that control thought, memory, and language.
Every day, scientists learn more about AD, but right now the cause of the
disease still is unknown, and there is no cure. An estimated 4 million
people in the United States suffer from AD.
The disease usually begins after age 65, and risk of AD goes up with age.
While younger people also may have AD, it is much less common. About 3
percent of men and women ages 65 to 74 have AD, and nearly half of those age
85 and older may have the disease. It is important to note, however, that
AD is not a normal part of aging.
AD is named after Dr. Alois Alzheimer, a German doctor. In 1906, Dr.
Alzheimer noticed changes in the brain tissue of a woman who had died of an
unusual mental illness. He found abnormal clumps (now called senile or
neuritic plaques) and tangled bundles of fibers (now called neurofibrillary
tangles). Today, these plaques and tangles in the brain are considered
hallmarks of AD. Scientists also have found other changes in the brains of
people with AD. There is a loss of nerve cells in areas of the brain that
are vital to memory and other mental abilities. There also are lower levels
of chemicals in the brain that carry complex messages back and forth between
billions of nerve cells. AD may disrupt normal thinking and memory by
blocking these messages between nerve cells.
AD begins slowly. At first, the only symptom may be mild forgetfulness.
People with AD may have trouble remembering recent events, activities, or the
names of familiar people or things. Simple math problems may become hard for
these people to solve. Such difficulties may be a bother, but usually they
are not serious enough to cause alarm.
However, as the disease goes on, symptoms are more easily noticed and become
serious enough to cause people with AD or their family members to seek
medical help. For example, people with AD may forget how to do simple
tasks, like brushing their teeth or combing their hair. They can no longer
think clearly; and they begin to have problems speaking, understanding,
reading, or writing. Later on, people with AD may become anxious or
aggressive, or wander away from home. Eventually, patients may need total
Doctors at specialized centers can diagnose probable AD correctly 80 to 90
percent of the time. They can find out whether there are plaques and tangles in the brain only by looking at a piece of brain tissue under a microscope. It can be painful and risky to remove brain tissue while a person is alive. Doctors cannot look at the tissue until they do an autopsy, which is an examination of the body done after a person dies.
Doctors may say that a person has "probable" AD. They will make this
diagnosis by finding out more about the person's symptoms. The following is
some of the information the doctor may need to make a diagnosis:
* A complete medical history
The doctor may ask about the person's general health and past medical
problems. He or she will want to know about any problems the person has
carrying out daily activities. The doctor may want to speak with the
person's family or friends to get more information.
* Basic medical tests
Tests of blood and urine may be done to help the doctor eliminate other
possible diseases. In some cases, testing a small amount of spinal fluid
also may help. In addition, scientists are busy trying to develop a test to
diagnose AD that will be easy and accurate.
* Neuropsychological tests
These are tests of memory, problem solving, attention, counting, and
language. They will help the doctor pinpoint specific problems the person
* Brain scans
The doctor may want to do a special test, called a brain scan, to take a
picture of the brain. There are several types of brain scans, including a
computerized tomography (CT) scan, a magnetic resonance imaging (MRI) scan,
or a positron emission tomography (PET) scan. By looking at a picture of
the brain, the doctor will be able to tell if anything does not look
normal. Information from the medical history and any test results help the
doctor rule out other possible causes of the person's symptoms. For
example, thyroid gland problems, drug reactions, depression, brain tumors,
and blood vessel disease in the brain can cause AD-like symptoms. Some of
these other conditions can be treated.
AD is a slow disease, starting with mild memory problems and ending with
severe mental damage. The course the disease takes and how fast changes
occur vary from person to person. Some people only have the disease for 5
years, while others may have it for as many as 20 years.
No treatment can stop AD. However, for some people in the early and middle
stages of the disease, the drug tacrine (also known as THA or Cognex) may
alleviate some cognitive symptoms. Also, some medicines may help control
behavioral symptoms of AD such as sleeplessness, agitation, wandering,
anxiety, and depression. Treating these symptoms often makes patients more
comfortable and makes their care easier for caregivers.
Scientists are testing new drugs for AD at many large teaching hospitals and
universities. Some of these drugs have shown promise in easing symptoms in
some patients. People with AD who want to help scientists test these
experimental drugs may be able to take part in clinical trials. To find
out more about these studies, contact the Alzheimer's Disease Education and
Referral (ADEAR) Center at the telephone number listed at the end of this
People with AD should go to their doctor regularly. The doctor will check to
see how the disease is progressing and treat any other illnesses that occur.
The doctor and other health professionals also can offer help and support to
patients and their families.
Most often, spouses or other family members provide the day-to-day care for
people with AD. As the disease gets worse, people often need more and more
care. This can be hard for caregivers and can affect their physical and
mental health, family life, jobs, and finances.
The Alzheimer's Association has chapters nationwide that provide educational
programs and support groups for caregivers and family members of people with
AD. For more information, contact the Alzheimer's Association listed at the
end of this fact sheet.
Scientists at research centers across the country are trying to learn what
causes AD and how to prevent it. They also are studying how memory loss
happens. They are looking for better ways to diagnose and treat AD, to
improve the abilities of people with the disease, and to support caregivers.
The major risk factors for AD are age and family history. Other possible
risk factors include a serious head injury and lower levels of education.
Scientists also are studying additional factors to see if they may cause the
disease. Some of these factors include:
* Genetic (inherited) factors
Scientists believe that genetic factors may be involved in more than half
of the cases of AD. For example, a protein called apolipoprotein E (ApoE)
may be important. Everyone has ApoE, which helps carry cholesterol in the
blood. However, the function of ApoE in the brain is less understood. The
ApoE gene has three forms. One form seems to protect a person from AD, and
another form seems to make a person more likely to develop the disease.
Scientists still need to learn a lot more about ApoE and its role in AD.
* Environmental factors
Scientists have found aluminum, zinc, and other metals in the brain tissue
of people with AD. They are studying these metals to see if they cause AD
or if they build up in the brain as a result of the disease.
Some scientists think that a virus may cause AD. They are studying viruses
that might cause the changes seen in the brain tissue of people with AD.
AD probably is not caused by any one factor. It is more likely to be several factors that act differently in each person.
For example, genetic factors alone may not be enough to cause the disease.
Other risk factors may combine with a person's genetic makeup to increase
his or her chance of developing the disease.
Scientists also are trying to develop a test that can detect or predict AD.
If the onset of the disease could be delayed for even a short time, the
number of people with the disease would drop. Delaying AD also would make
the quality of life better for older people and lead to savings in health
Other research is aimed at helping both patients and caregivers cope with the
patients' loss of abilities and the stress this causes. For example,
researchers are studying ways to manage problem behaviors in patients, such
as wandering and agitation. Still other scientists are evaluating services
and programs for patients and caregivers, including respite care. Respite
care covers a variety of situations in which someone else cares for the
patient for a period of time, giving family caregivers temporary relief.
The National Institute on Aging, the Federal Government's lead agency for AD
research, funds Alzheimer's Disease Centers located throughout the United
States. The centers carry out a wide range of research, including studies on
the causes, diagnosis, treatment, and management of AD. To obtain a list of
the centers, contact the ADEAR Center listed below.
For More Information
To learn about support groups, services, research centers, and publications
about AD, contact the following groups:
919 N Michigan Avenue, Suite 1000
Chicago, IL 60611-1676
This non-profit group supports families and caregivers of AD patients.
Chapters nationwide provide referrals to local resources and services, and
sponsor support groups and educational programs.
Alzheimer's Disease Education and Referral (ADEAR) Center
PO Box 8250
Silver Spring, MD 20907-8250
This service of the National Institute on Aging is funded by the Federal
Government. It offers information and publications on diagnosis, treatment,
patient care, caregiver needs, long-term care, education and training, and
research related to AD. Staff respond to telephone and written requests and
make referrals to national- and State-level resources.
1112 16th Street NW, Suite 100
Washington, DC 20036
This service of the National Association of Area Agencies on Aging provides
information about and referrals to respite care and other home and community
services offered by State and Area Agencies on Aging.
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
National Institutes of Health
National Institute on Aging