What Is It?

Alzheimer's disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and other thinking skills, and eventually even the ability to carry out the simplest tasks.

Ultimately, the person with AD dies, often years earlier than he/she would have otherwise. In most people with AD, symptoms first appear after age 60. The brains of people with AD have an abundance of two abnormal structures—amyloid plaques and neurofibrillary tangles. A third characteristic change is the loss of connections between nerve cells (neurons) in the brain. Learn more.

Who Gets It?

Alzheimer's disease becomes more common as people get older. Today it affects more than 5.3 million Americans, according to estimates from the Alzheimer's Association. As the baby-boom generation moves through retirement, that number could soar to more than 11 million by 2040. One out of eight people age 65 or older has Alzheimer's. The number of people with the disease doubles for every 5-year age interval beyond age 65. Learn more.

Who Is At Risk?

Age is the best established risk factor for Alzheimer's. The genetic make-up inherited from parents may also influence risk of developing the disease, and when. Other non-genetic, environmental, or lifestyle factors might play a role in brain health and the development or prevention of Alzheimer's disease. Many of these can be controlled or mitigated, including physical activity, diet, control of chronic diseases, social engagement, and intellectual stimulation. Learn more.

How Can People Find Out If They Have It?

People who are concerned about a serious memory problem should talk with their doctor. The doctor may be able to diagnose the problem or make a referral to a specialist in neurology or geriatric psychiatry. Health care professionals who specialize in Alzheimer's can recommend ways to manage the problem or suggest treatment or services that might help. Learn more.

Can It Be Treated?

There is no cure for Alzheimer's disease, but current treatments focus on helping people maintain mental function, manage behavioral symptoms, and slow or delay symptoms. Four medications are approved by the U.S. Food and Drug Administration to treat AD. These drugs don't change the underlying disease process and may help only for a few months to a few years.

Behavioral symptoms may accompany memory problems and can include sleeplessness, agitation, wandering, anxiety, anger, and depression. Scientists are studying new treatments to manage them. Treating behavioral symptoms often makes people with AD more comfortable and makes their care easier for caregivers. Learn more.

Who Else Is Affected?

There are nearly 10 million Americans providing 8.5 billion hours of unpaid care to people with Alzheimer's disease or other dementias - time valued at $94 billion, according to the Alzheimer's Association. Seventy percent of people with Alzheimer's live at home, cared for by family and friends. The largest group of family caregivers is spouses, followed by daughters, daughters-in-law, sons, siblings, and grandchildren. About three in five caregivers say their children aged 8 to 21 are involved in caring for a loved one with Alzheimer's disease, according to a 2008 Harris Interactive poll.

In addition to the families and friends, our society as a whole is affected. Today, the direct costs to Medicare and Medicaid for care of people with Alzheimer's and other dementias and the indirect costs to business for employees who are caring for Alzheimer's are estimated at more than $148 billion annually. Learn more.

Can It Be Prevented?

No treatments or drugs have yet been proven to prevent or delay AD, but people can take some actions that are beneficial for healthy aging and that also might reduce the effect of possible risk factors for AD. You can exercise regularly, eat a healthy diet that is rich in fruits and vegetables, engage in social and intellectually stimulating activities, control type 2 diabetes, lower high blood pressure levels, lower high blood cholesterol levels, and maintain a healthy weight. These actions lower the risk of other diseases and help maintain and improve overall health and well-being, but will not necessarily prevent or delay AD in any one person. Even if these actions were eventually proven effective, they might not offset a person's individual genetic and other risk factors enough to prevent the development of AD. Learn more.

What's Being Done About It?

Thirty years ago, we knew very little about AD. Since then, scientific research - supported by the National Institute on Aging and other components of the National Institutes of Health, the Alzheimer's Association, and other organizations - has led to important advances in our knowledge about AD and to the development of promising new drugs and treatment strategies. Today, scientists are investigating many approaches to treat, prevent, or cure Alzheimer's, with 91 drugs in clinical trials as of 2008 and more in the pipeline awaiting FDA approval to enter human testing. Learn more.

How Can I Help?

Clinical trials to test new treatments and interventions are an essential part of AD research. At least 50,000 volunteers, both with and without Alzheimer's, are urgently needed to participate in more than 175 actively enrolling Alzheimer's disease trials and studies in the U.S. To reach that goal, at least half a million volunteers must be screened. To find out more, contact the National Institute on Aging's Alzheimer's Disease Education and Referral (ADEAR) Center at 1-800-438-4380 or at the website www.nia.nih.gov/alzheimers.

There are many ways to join the fight against Alzheimer's disease, such as participating in research, supporting people with the disease with donations of time, help, or money, and other activities. To find out more, you can contact the Alzheimer's Association, which invites the public to become "Alzheimer's Advocates," at 1-800-272-3900 or at the website www.alz.org.

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Visit our collaborators' websites to learn more:

Alzheimer's Disease (AD)

A progressive degenerative disease of the brain that causes impairment of memory and other cognitive abilities.

Amyloid Precursor Protein (APP)

The larger protein from which beta-amyloid is formed.

ApoE Gene

A gene that codes for a protein that carries cholesterol to and within cells; different forms of the ApoE gene are associated with differing risks for late-onset Alzheimer's disease. This gene may be referred to as a risk factor gene or a "susceptibility gene" because one form of the gene, called APOE4, is associated with the risk of developing late onset AD.


Derived from the amyloid precursor protein and found in plaques, the insoluble deposits outside neurons. May also be called A-beta.

Beta-Amyloid Plaque

A largely insoluble deposit found in the space between nerve cells in the brain. The plaques in Alzheimer's disease are made of beta-amyloid and other molecules, surrounded by non-nerve cells (glia) and damaged axons and dendrites from nearby neurons.

Cognitive Reserve

The brain's ability to operate effectively even when some damage to cells or brain cell communications has occurred.


A broad term referring to a decline in cognitive function that interferes with daily life and activities. Alzheimer's disease is one form of dementia.

Functional MRI (fMRI)

An adaptation of an MRI (see magnetic resonance imaging) technique that measures brain activity during a mental task, such as one involving memory, language, or attention.

Hippocampal Formation

A structure in the brain that plays a major role in learning and memory and is involved in converting short-term to long-term memory. Also called the hippocampus.


The process by which the body responds to cellular injury by attempting to eliminate foreign matter and damaged tissue.

Insulin Resistance

A condition in which the pancreas makes enough insulin, but the cells do not respond properly to it; characterizes and precedes type 2 diabetes.

Magnetic Resonance Imaging (MRI)

A diagnostic and research technique that uses magnetic fields to generate a computer image of internal structures in the body.

Mild Cognitive Impairment (MCI)

A condition in which a person has cognitive problems greater than those expected for his or her age. Amnestic MCI includes memory problems, but not the personality or other cognitive problems that characterize AD.

Neurodegenerative Disease

A disease characterized by a progressive decline in the structure and function of brain tissue. These diseases include AD, Parkinson's disease, frontotemporal lobar degeneration, and dementia with Lewy bodies. They are usually more common in older people.


Clusters of a small number of beta-amyloid peptides.

Oxidative Damage

Damage that can occur to cells when they are exposed to too many free radicals.

Pittsburgh Compound B (PiB)

The radioactive tracer compound used during a PET (see Positron Emission Tomography) scan of the brain to show beta-amyloid deposits.

Pittsburgh Compound B (PiB)

The radioactive tracer compound used during a PET (see Positron Emission Tomography) scan of the brain to show beta-amyloid deposits.


The tiny gap between nerve cells across which neurotransmitters and nerve signals pass.


A protein that helps to maintain the structure of microtubules in normal nerve cells. Abnormal tau is a principal component of the paired helical filaments in neurofibrillary tangles.


A protein that helps to maintain the structure of microtubules in normal nerve cells. Abnormal tau is a principal component of the paired helical filaments in neurofibrillary tangles.


Normal Aging

Genetic Risk Factor

Dominant and Recessive Genes

Genes and Proteins

Protein-Misfolding Disease



Disease-Modifying Drug

Transgenic Mice

An animal that has had a gene (such as the human APP gene) inserted into its chromosomes for the purpose of research. Mice carrying a mutated human APP gene often develop plaques in their brains as they age.



Insulin & Insulin Resistance

Susceptibility Gene

A variant in a cell's DNA that does not cause a disease by itself but may increase the chance that a person will develop a disease.

Susceptibility Genes

A variant in a cell's DNA that does not cause a disease by itself but may increase the chance that a person will develop a disease.

Genome-Wide Association Study

Vascular Disease



Normal Aging