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Alzheimer’s Disease
FA C T S H E E T
A
lzheimer’s disease (AD) is an Changes in the Brain in AD
irreversible, progressive brain
disease that slowly destroys Although we still don’t know what
memory and thinking skills, and even- starts the AD process, we do know that
tually even the ability to carry out the damage to the brain begins as many
simplest tasks. In most people with AD, as 10 to 20 years before any problems
symptoms first appear after age 60. are evident. Tangles begin to develop
deep in the brain, in an area called the
AD is the most common cause of de- entorhinal cortex, and plaques form in
mentia among older people. Dementia other areas. As more and more plaques
is the loss of cognitive functioning— and tangles form in particular brain
thinking, remembering, and reason- areas, healthy neurons begin to work
ing—to such an extent that it interferes less efficiently. Then, they lose their
with a person’s daily life and activities. ability to function and communicate
According to recent estimates, as many with each other, and eventually they
as 2.4 to 4.5 million Americans are die. This damaging process spreads
living with AD. to a nearby structure, called the hippo-
campus, which is essential in forming
AD is named after Dr. Alois Alzheimer.
memories. As the death of neurons
In 1906, Dr. Alzheimer noticed changes
increases, affected brain regions begin
in the brain tissue of a woman who
to shrink. By the final stage of AD,
had died of an unusual mental illness.
damage is widespread and brain tissue
Her symptoms included memory loss,
has shrunk significantly.
language problems, and unpredictable
behavior. After she died, he examined Very Early Signs and Symptoms
her brain and found many abnormal
clumps (now called amyloid plaques) Memory problems are one of the first
and tangled bundles of fibers (now signs of AD. Some people with memory
called neurofibrillary tangles). Plaques problems have a condition called
and tangles in the brain are two of the amnestic mild cognitive impairment
main features of AD. The third is the (MCI). People with this condition have
loss of connections between nerve cells more memory problems than normal
(neurons) in the brain. for people their age, but their symptoms
Alzheimer’s Disease Education & Referral (ADEAR) Center
A Service of the National Institute on Aging
National Institutes of Health
U.S. Department of Health and Human Services
are not as severe as those with AD. More
people with MCI, compared with those
without MCI, go on to develop AD.
Other changes may also signal the very
early stages of AD. For example, recent
research has found links between some
movement difficulties and MCI. Research-
ers also have seen links between some
problems with the sense of smell and
cognitive problems. Brain imaging and
biomarker studies of people with MCI and
those with a family history of AD are begin-
ning to detect early changes in the brain
like those seen in AD. These findings will
need to be confirmed by other studies but
appear promising. Such findings offer
hope that some day, we may have tools
that could help detect AD early, track the
course of the disease, and monitor response As Alzheimer’s disease progresses, neuro-
to treatments. fibrillary tangles spread throughout the brain
(shown in blue). Plaques also spread through-
Mild AD out the brain, starting in the neocortex. By
the final stage, damage is widespread and
As AD progresses, memory loss continues brain tissue has shrunk significantly.
and changes in other cognitive abilities
appear. Problems can include getting They may have hallucinations, delusions,
lost, trouble handling money and paying and paranoia, and may behave impulsively.
bills, repeating questions, taking longer
to complete normal daily tasks, poor Severe AD
judgment, and mood and personality
By the final stage, plaques and tangles
changes. People often are first diagnosed
have spread throughout the brain and
in this stage.
brain tissue has shrunk significantly.
Moderate AD People with severe AD cannot communi-
cate and are completely dependent on
In this stage, damage occurs in areas of others for their care. Near the end, the
the brain that control language, reasoning, person may be in bed most or all of the
sensory processing, and conscious thought. time as the body shuts down.
Memory loss and confusion increase, and
people begin to have problems recognizing What Causes AD
family and friends. They may be unable
to learn new things, carry out tasks that Scientists don’t yet fully understand what
involve multiple steps (such as getting causes AD, but it is clear that it develops
dressed), or cope with new situations. because of a complex series of events that
2
take place in the brain over a long gene called APOE to late-onset AD. This
period of time. It is likely that the gene has several forms. One of them,
causes include genetic, environmental, APOE e4, increases a person’s risk of
and lifestyle factors. Because people getting the disease. About 40 percent
differ in their genetic make-up and life- of all people who develop late-onset AD
style, the importance of these factors carry this gene. However, carrying the
for preventing or delaying AD differs APOE e4 form of the gene does not
from person to person. necessarily mean that a person will
develop AD, and people carrying no
The Basics of AD APOE e4 forms can also develop AD.
Scientists are conducting studies to Scientists think that other risk-factor
learn more about plaques, tangles, and genes exist as well. A possible new one,
other features of AD. They can now SORL1, was discovered in 2007. Large-
visualize plaques by imaging the brains scale genetic research studies are look-
of living individuals. They are also ing to find other genes. For more about
exploring the very earliest steps in the this area of research, see the Alzheimer’s
disease process. Findings from these Disease Genetics Fact Sheet, available at
studies will help them understand the www.nia.nih.gov/Alzheimers.
causes of AD.
Lifestyle Factors
One of the great mysteries of AD is why
it largely strikes older adults. Research A nutritious diet, exercise, social en-
on how the brain changes normally with gagement, and mentally stimulating
age is shedding light on this question. pursuits can all help people stay healthy.
For example, scientists are learning New research suggests the possibility
how age-related changes in the brain that these factors also might help to
may harm neurons and contribute to reduce the risk of cognitive decline and
AD damage. These age-related changes AD. Scientists are investigating asso-
include inflammation and the produc- ciations between cognitive decline and
tion of unstable molecules called free heart disease, high blood pressure,
radicals. diabetes, and obesity. Understanding
these relationships and testing them in
Genetics clinical trials will help us understand
whether reducing risk factors for these
In a very few families, people develop
diseases may help with AD as well.
AD in their 30s, 40s, and 50s. These
people have a mutation, or permanent
How AD Is Diagnosed
change, in one of three genes that they
inherited from a parent. We know that AD can be definitively diagnosed only
these gene mutations cause AD in these after death by linking clinical course
“early-onset” familial cases. with an examination of brain tissue and
pathology in an autopsy. But doctors
However, most people with AD have
now have several methods and tools to
“late-onset” AD, which usually develops
help them determine fairly accurately
after age 60. Many studies have linked a
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whether a person who is having treatments to see which are most effec-
memory problems has “possible AD” tive and for whom they work best. (See
(the symptoms may be due to another the box, below, for more information.)
cause) or “probable AD” (no other cause
for the symptoms can be found). To
diagnose AD, doctors:
Participating in
ask questions about the person’s
Clinical Trials
n
overall health, past medical prob-
lems, ability to carry out daily People with AD, those with MCI, those
activities, and changes in behavior with a family history of AD, and healthy
and personality people with no memory problems and no
family history of AD may be able to take
n conduct tests of memory, problem part in clinical trials. Study volunteers
solving, attention, counting, and help scientists learn about the brain in
healthy aging as well as what happens in
language AD. Results of AD clinical trials are used
to improve prevention and treatment
n carry out medical tests, such as tests approaches. Participating in clinical trials
of blood, urine, or spinal fluid is an effective way to help in the fight
against AD.
n perform brain scans, such as a com-
puterized tomography (CT) scan or NIA, which is part of the National
a magnetic resonance imaging (MRI) Institutes of Health (NIH), leads the
test Federal Government’s research efforts
on AD. NIA-supported Alzheimer’s
These tests may be repeated to give Disease Centers located throughout the
United States conduct many clinical trials
doctors information about how the
and carry out a wide range of research,
person’s memory is changing over including studies of the causes, diag-
time. nosis, and management of AD. NIA
also sponsors the Alzheimer’s Disease
Early diagnosis is beneficial for several Cooperative Study (ADCS), a consortium
reasons. Having an early diagnosis and of leading AD researchers throughout
starting treatment in the early stages the U.S. and Canada who conduct clinical
of the disease can help preserve func- trials on promising AD treatments.
tion for months to years, even though
To find out more about AD clinical trials,
the underlying AD process cannot be talk to your health care provider or con-
changed. Having an early diagnosis tact NIA’s ADEAR Center at 1-800-438-
also helps families plan for the future, 4380. Or, visit the ADEAR Center clinical
make living arrangements, take care trials database at www.nia.nih.gov/
of financial and legal matters, and Alzheimers/ResearchInformation/
ClinicalTrials. You also can sign up for
develop support networks.
email alerts that let you know when new
clinical trials are added to the database.
In addition, an early diagnosis can
More information about clinical trials
provide greater opportunities for people is available at www.ClinicalTrials.gov.
to get involved in clinical trials. In a
clinical trial, scientists test drugs or
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How AD Is Treated symptoms to think about addressing the
underlying disease process. In ongoing
AD is a complex disease, and no single AD clinical trials, scientists are looking
“magic bullet” is likely to prevent or cure at many possible interventions, such as
it. That’s why current treatments focus on cardiovascular treatments, antioxidants,
several different aspects, including helping immunization therapy, cognitive training,
people maintain mental function; manag- and physical activity.
ing behavioral symptoms; and slowing,
delaying, or preventing AD. Supporting Families and
Caregivers
Helping People with AD Maintain
Mental Function Caring for a person with AD can have high
physical, emotional, and financial costs.
Four medications are approved by the The demands of day-to-day care, changing
U.S. Food and Drug Administration to treat family roles, and difficult decisions about
AD. Donepezil (Aricept®), rivastigmine placement in a care facility can be hard
(Exelon®), and galantamine (Razadyne®) to handle. Researchers are learning a lot
are used to treat mild to moderate AD about AD caregiving, and studies are help-
(donepezil can be used for severe AD as ing experts develop new ways to support
well). Memantine (Namenda®) is used to caregivers.
treat moderate to severe AD. These drugs
work by regulating neurotransmitters (the Becoming well-informed about AD is one
chemicals that transmit messages between important long-term strategy. Programs
neurons). They may help maintain think- that teach families about the various stages
ing, memory, and speaking skills, and of AD and about flexible and practical
help with certain behavioral problems. strategies for dealing with difficult care-
However, these drugs don’t change the giving situations provide vital help to those
underlying disease process and may help who care for people with AD.
only for a few months to a few years.
Developing good coping skills and a strong
Managing Behavioral Symptoms support network of family and friends also
are important ways that caregivers can
Common behavioral symptoms of AD in- help themselves handle the stresses of car-
clude sleeplessness, agitation, wandering, ing for a loved one with AD. For example,
anxiety, anger, and depression. Scientists staying physically active provides physical
are learning why these symptoms occur and emotional benefits.
and are studying new treatments—drug
and non-drug—to manage them. Treating Some AD caregivers have found that
behavioral symptoms often makes people participating in an AD support group is
with AD more comfortable and makes their a critical lifeline. These support groups
care easier for caregivers. allow caregivers to find respite, express
concerns, share experiences, get tips, and
Slowing, Delaying, or Preventing AD receive emotional comfort. The Alzheimer’s
AD research has developed to a point Association, Alzheimer’s Disease Centers,
where scientists can look beyond treating and many other organizations sponsor
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in-person and online AD support groups Research supported by NIA and other
across the country. There are a growing organizations has expanded knowledge
number of groups for people in the early of brain function in healthy older people,
stage of AD and their families. Support identified ways we might lessen normal
networks can be especially valuable age-related declines in mental function,
when caregivers face the difficult deci- and deepened our understanding of AD.
sion of whether and when to place a Many scientific and clinical fields are
loved one in a nursing home. now working together to untangle the
genetic, biological, and environmental
Advancing Our Understanding factors that, over many years, ultimately
result in AD. This effort is bringing us
Thirty years ago, we knew very little
closer to the day when we will be able
about AD. Since then, scientists have
to manage successfully or even prevent
made many important advances.
this devastating disease.
For More Information trials database; the AD Library database;
and more.
To learn about support groups, services,
research centers, research studies, and Alzheimer’s Association
publications about AD, contact the 225 N. Michigan Avenue, Floor 17
following resources: Chicago, IL 60601-7633
800-272-3900 (toll-free)
Alzheimer’s Disease Education 866-403-3073 (TDD/toll-free)
and Referral (ADEAR) Center www.alz.org
.O.
P Box 8250
Silver Spring, MD 20907-8250 Alzheimer’s Foundation of America
800-438-4380 (toll-free) 322 Eighth Avenue, 7th Floor
www.nia.nih.gov/Alzheimers New York, NY 10001
866-AFA-8484 (866-232-8484; toll-free)
A service of the National Institute on www.alzfdn.org
Aging (NIA), the ADEAR Center offers
information and publications for families, Eldercare Locator
caregivers, and professionals on diagno- 800-677-1116 (toll-free)
sis, treatment, patient care, caregiver www.eldercare.gov
needs, long-term care, education and
Family Caregiver Alliance
training, and research related to AD.
180 Montgomery Street, Suite 1100
Staff members answer telephone, email,
San Francisco, CA 94104
and written requests and make referrals
800-445-8106 (toll-free)
to local and national resources. The
www.caregiver.org
ADEAR website provides free, online
publications in English and Spanish; NIHSeniorHealth
email alert and online Connections www.nihseniorhealth.gov
newsletter subscriptions; an AD clinical
NIH Publication No. 08-6423 6 November 2008
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