What is Alzheimer's disease?

Alzheimer's disease (pronounced Altz-hi-merz) is a progressive, degenerative disease that attacks the brain and results in impaired memory, thinking and behavior. It affects an estimated 2.5 million American adults.

When it was first described by German physician Alois Alzheimer in 1907, Alzheimer's disease was considered a rare disorder. Today, it is recognized as the most common cause of dementia.

Dementia is not a disease itself but a group of symptoms that characterize certain diseases and conditions. In the case of Alzheimer's disease, the dementia includes a decline in intellectual functioning that is severe enough to interfere with the ability to perform routine activities.

The second most common form of dementia is multi-infarct dementia, which is caused by vascular disease and strokes. Other causes of dementia are Huntington's disease, Parkinson's disease, Pick's disease and Creutzfeldt-Jakob disease.

There also are a number of conditions that cause dementialike symptoms: depression, drug reactions, thyroid disorders, nutritional deficiencies, brain tumors, head injuries, alcoholism, infections (meningitis, syphilis, AIDS) and hydrocephalus.

Alzheimer's disease is distinguished from other forms of dementia by characteristic changes in the brain that are visible only upon microscopic examination.

At autopsy, Alzheimer's disease brains show the presence of tangles of fibers (neurofibrillary tangles) and clusters of degenerating nerve endings (neuritic plaques) in areas of the brain that are important for memory and intellectual functions.

Another characteristic of Alzheimer's disease is the reduced production of certain brain chemicals, especially acetylcholine and somatostatin. These chemicals are necessary for normal communication between nerve cells.

Who is affected by Alzheimer's disease?

Alzheimer's disease is more likely to occur as a person gets older. Although less than one percent of people age 65 are affected by Alzheimer's disease, it is present in an estimated 25 percent of those age 85 or older. Alzheimer's disease can occur in middle age as well. The youngest documented case is that of a 28-year-old individual.

Alzheimer's disease also affects the family of an Alzheimer patient. The emotional, social and financial costs of caring for an Alzheimer patient are high. Family members also often risk their own health in order to care for the Alzheimer patient at home.

What are the symptoms?

Alzheimer's disease has a gradual onset. Symptoms include difficulty with memory and loss of intellectual abilities severe enough to interfere with routine work or social activities. The Alzheimer patient also may experience confusion, language problems (such as trouble finding words), poor or decreased judgment, disorientation in place and time and changes in behavior or personality.

How quickly these changes occur in an Alzheimer patient will vary from person to person. Eventually, the disease leaves its victims totally unable to care for themselves. The course of the disease averages eight years from the time symptoms first appear, although Alzheimer's disease has been known to last as long as 25 years.

How is Alzheimer's disease diagnosed?

At this time, there is no single diagnostic test for Alzheimer's disease. A complete physical, psychiatric and neurologic evaluation by a physician experienced in the diagnosis of dementing disorders should be obtained when symptoms are noticed.

The examination should include a detailed medical history, mental status test, neuropsychological testing, blood work, urinalysis, chest x-ray, electroencephalography (EEG), computerized tomography (CT scan) and electrocardiogram (EKG). Such an evaluation is essential to determine whether the dementia is the result of a treatable illness.

When this kind of a detailed examination is done, the accuracy of diagnosis is about 90 percent. However, the only way to confirm a diagnosis of Alzheimer's disease is to examine brain tissue under a microscope.

What causes Alzheimer's disease?

Scientists are still looking for the cause of Alzheimer's disease, and their research is pointing in several directions.

For one form of the disease called Familial or Uncommon Alzheimer's Disease, there is strong evidence that a defect exists in a single gene on Chromosome 21.

However, for most Alzheimer's disease patients the genetic involvement is less clear. Although there does seem to be a genetic predisposition for the disease, other factors influence whether or not an individual develops Alzheimer's disease.

Scientists continue to explore the importance of such things as a slow virus; environmental toxins, such as aluminum; and

other physical conditions of an individual that may interact with the genetic defect.

Is Alzheimer's disease fatal?

Although Alzheimer's disease is associated with a shortened lifespan, the slow, progressive nature of the disease often means the patient will live for several years after diagnosis.

Alzheimer's disease eventually leaves the patient physically less resistant to infections, such as pneumonia, which may be fatal. In addition, Alzheimer's disease generally affects an older population that is subject to other chronic illnesses, and those illnesses, too, may often be the cause of death.

Can Alzheimer's disease be treated or cured?

At this time, there is no treatment or cure available to stop or reverse the mental deterioration of Alzheimer's disease. However, new research findings give reason for hope. Several drugs used to relieve the symptoms of memory loss are in clinical trials.

Other medications are available now to assist in managing some of the most troubling symptoms of Alzheimer's disease. Under a doctor's supervision, medication can be used to control depression, behavioral disturbances and sleeplessness.

Can Alzheimer's disease be prevented?

Prevention is not possible at this time because the cause of the disease is not known. However, advances in science are bringing us closer to answers that can lead to treatments and/or strategies for prevention. Meanwhile, focus on improved care and support for the caregiver are helping to ease the burden of Alzheimer's disease.

Is there help for people affected by Alzheimer's disease?

The Alzheimer's Association is the only national voluntary organization dedicated to providing support and assistance to Alzheimer patients and their families. The Alzheimer's Association is continuing research into the cause, treatment and cure of Alzheimer's disease, as well as ways to improve the care and management of current Alzheimer patients.

The Alzheimer's Association has more than 1,200 support groups and 190 Chapters nationwide. For more information on Alzheimer's disease and the Alzheimer's Association or to volunteer in the fight against Alzheimer's disease, call the Association's toll-free number for the location of the Chapter nearest you.


Dementia -- This is not a disease in itself but a group of symptoms that characterize certain diseases and conditions. The major symptoms involve a decline in intellectual functioning that is severe enough to interfere with routine activities. Alzheimer's disease is the most common form of dementia.

Senility -- This label often was used to describe an individual 65 years or older with dementia. Senility used to be considered a normal part of aging. Today, physicians recognize that dementia is not a normal part of aging but the result of a disease such as Alzheimer's disease.

Senile dementia/pre-senile dementia -- Senile dementia is a label that used to apply to patients whose symptoms of dementia appeared after age 65. Pre-senile dementia is a label that used to apply to dementia victims who were younger than age 65. These distinctions have largely been eliminated. Today, most cases of dementia in both groups of patients are diagnosed as Alzheimer's disease.

Chronic organic brain syndrome -- This label is sometimes given to patients with a collection of symptoms such as memory loss, disorientation, confusion, personality changes and inability to carry out normal daily activities. The preferred term for these symptoms is dementia or dementing illness.

Hardening of the arteries -- The correct medical term is arteriosclerosis. The dementia symptoms associated with arteriosclerosis result only when multiple cerebral infarcts (strokes) have occurred. This condition is called multi-infarct dementia.

This brochure is one of a series made available by the Alzheimer's Association with underwriting from American Contract Bridge League, Louis N. Cassett Foundation, the Coca Cola Foundation, Ittleson Foundation, Inc., and Million Dollar Round Table Foundation.