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neurologychannel |
Introduction
Alzheimer's disease (AD) is the most common cause of dementia in older people. 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.
Symptoms
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 care.
Diagnosis
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 has.
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.
Treatment
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 fact sheet.
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.
Research
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.
Viruses
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 care costs.
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.
This information was developed by the Alzheimer's Disease Education and Referral Center and is herewith used with permission.
Alzheimer's Disease Education and Referral; Center. Alzheimer's Disease Fact Sheet. Available at: http://www.alzheimers.org/pubs/adfact.html. Accessed December 6, 1999.
The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, Arbor Publishing Corp, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.