• Medicine
  • Encyclopedias almanacs transcripts and maps
  • Multiple: Alzheimer Disease

Multiple: Alzheimer Disease

views updated

Multiple: Alzheimer Disease

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

Alzheimer disease, or AD, is a terminal disease of the central nervous system that has no effective treatment or cure. Its most notable symptom is dementia—the loss of a person's memory and other cognitive functions beyond the effects of normal aging. It is named for Alois Alzheimer (1864–1915), a German doctor who first described a patient with the disease at a medical meeting in 1906.

Description

AD affects a person's ability to think clearly, to remember, to speak, to pay attention, and to solve problems. The disease is characterized by the buildup of abnormal protein deposits in the brain, some of which look like clumps or plaques under the microscope and others that look like tangled fibers. Researchers do not yet know whether these abnormal proteins are causes of AD or whether they are a consequence of the disease.

In addition, the cells in the part of the brain called the cerebral cortex begin to die and the tissue in that part of the brain begins to shrink. The cortex is the part of the brain that governs memory, the ability to pay attention, to use language, and to think; this helps to explain why these mental functions are gradually lost in patients with Alzheimer disease.

As the disease progresses, the destruction of brain tissue spreads to the areas of the brain that govern the emotions, and finally to the brain stem, which controls basic body functions like breathing and swallowing. Most patients with AD die from pneumonia or another infectious disease before the brain stem is completely destroyed.

There are two basic forms of AD, an early-onset form that affects people younger than 60 years of age and is transmitted within families; and a late-onset form that affects people over 60.

Demographics

AD is presently the third leading cause of death in American adults, after cancer and heart disease. It is thought to affect 5 million adults in the United States as of the early 2000s—14 percent of the population over sixty-five. The frequency of Alzheimer disease increases with age; about 40 percent of people over eighty have AD. The lifetime risk of an individual's developing AD is between one chance in four and one chance in two.

Women are at greater risk than men of developing AD in old age, although the reasons for this difference are not clear. Race does not appear to be a risk factor for AD.

Famous People Who Had AD

Alzheimer disease can strike anyone in any walk of life; it has claimed the lives of a number of well-known people:

Causes and Symptoms

The causes of AD are not fully understood. Early-onset AD, which is sometimes called familial Alzheimer disease, is caused by mutations of certain genes on chromosomes 1, 14, 19, and 21. This form of AD accounts

for only 4–5 percent of cases, however. Most cases of Alzheimer's are considered sporadic, which means that they occur at random. Scientists think, however, that as many as 80 percent of these sporadic cases are influenced by genetic risk factors that have not yet been completely identified. Over 400 genes had been tested for links to AD as of 2007.

Other factors that have been identified as increasing a person's risk of developing AD include:

  • High blood pressure or high blood cholesterol levels
  • Heart disease or stroke
  • Head injury
  • Diabetes
  • Female sex

Although some researchers in the 1970s thought that aluminum in drinking water, antiperspirant deodorants, and the diet might be a risk factor for AD, those theories have been disproved.

The symptoms of Alzheimer disease change as the disease progresses. Doctors generally describe four stages in the development of AD:

  • Mild cognitive impairment. This phase can begin as long as eight years before a person is diagnosed with AD. The affected individual has some short-term memory loss and loses the ability to learn new information.
  • Early dementia. The person begins to have language problems as well as memory problems, although they can still communicate with others. They may begin to need help with some activities of daily life. Many patients are diagnosed at this point because family and friends begin to notice changes in behavior or general loss of functioning.
  • Moderate dementia. The person loses the ability to live independently and suffers further memory loss. Emotional control is lost; some patients with AD become physically violent toward others at this point as well as generally irritable or weepy. About 30 percent of patients in this stage have hallucinations and become unable to identify close relatives.
  • Advanced dementia. The person loses the ability to talk except for occasional words, loses control of bowel and bladder functions, becomes unable to feed him or herself, and may be completely bedridden.

Diagnosis

There is no definitive test for AD except analyzing a sample of brain tissue, which can only be performed after the person dies. When a person first begins to show signs of dementia, however, doctors can arrive at a tentative diagnosis of AD through a series of tests and imaging studies. These may include:

  • Laboratory tests of blood and urine samples. These tests are done to rule out infections or heart problems that might affect memory and other cognitive functions.
  • Imaging studies, usually an MRI or a CT scan. These are done to rule out brain tumors, Parkinson disease, infections of the brain, or stroke.
  • Mental status examination (MSE). This type of test evaluates the person's awareness of their location in time and place; their ability to follow simple instructions; their short-term memory; and their overall mood. The tests may include being asked to name the current president, to spell a word backward, or to copy a design on a piece of paper.
  • A PiB PET scan. PiB stands for Pittsburgh Compound B, a chemical used in imaging tests which was shown in 2007 to identify the location of abnormal protein deposits in the brain of a patient with AD. This technique is not yet widely available in the United States, however.

Treatment

There is no effective treatment for AD. There are three drugs that have been approved by the Food and Drug Administration (FDA) to slow down the loss of brain function in patients with AD, but these drugs work for only about six to twelve months, and benefit only half the people who take them. Patients who become depressed, agitated or violent can be given medications to help control these symptoms. There are no effective surgical treatments for Alzheimer disease.

Patients in the final stages of Alzheimer disease are kept clean and made as comfortable as possible. They may be given fluids and nutrients intravenously if they are unable to swallow. Death is most often caused because the patient stops breathing.

Prognosis

There is no cure for Alzheimer disease. Most people live between three and ten years after being diagnosed with the disorder, although some have lived as long as twenty years after diagnosis. Death usually comes as the result of pneumonia, a urinary tract infection, or complications following a fall.

Prevention

There is no way to prevent the development of the familial form of AD in people who have the genes for the disease. With regard to sporadic late-onset AD, research is under way to identify steps that people can take to lower their risk of developing Alzheimer disease in old age. What researchers think as of the early 2000s is that the best way to protect the brain is to protect the heart: eating a healthful diet rich in fruits and vegetables, exercising regularly, getting treatment for high blood pressure, and keeping mentally active are all recommended. Such activities as playing chess, solving crossword puzzles, and social get-togethers with other people have been reported to delay the onset of AD or reduce its severity. Another suggestion is to take Advil or Motrin, as anti-inflammatory drugs may also lower the risk of AD.

The Future

Alzheimer disease is a major concern to policy makers in the twenty-first century as the proportion of elderly people in the general population continues to increase. Since the risk of developing AD doubles every five years after a person reaches 65, the possibility of having large numbers of people requiring several years of skilled nursing care at the end of their lives is worrisome to many doctors.

At present, many patients in the early and middle stages of the disease are cared for by relatives. The stress of caring for a parent, sibling, or spouse with AD is very high; many caregivers end up having to quit their jobs in order to care for the sick family member. In addition, the emotional strain of caring for someone who no longer recognizes the caregiver and may be openly violent or wander away from home can be exhausting. Doctors are increasingly aware that caregivers of Alzheimer patients have a high rate of depression and physical illnesses related to stress.

Research on AD is focused on preventive strategies. One possibility is developing a drug that can clear the abnormal proteins involved in

AD from the brain tissue or prevent them from forming in the first place. Some experimental drugs of this type are currently undergoing clinical trials. Some researchers predict that there will be a major breakthrough in treating Alzheimer disease by 2020.

SEE ALSO Creutzfeldt-Jakob disease; Huntington disease

WORDS TO KNOW

Brain stem: The lower part of the brain directly connected to the spinal cord. It controls such basic body functions as breathing and consciousness.

Cerebral cortex: The part of the brain that controls thinking, memory, paying attention, decision making, and using language.

Dementia: Loss of memory and other mental functions related to thinking or problem-solving.

For more information

BOOKS

Alzheimer's Association. Basics of Alzheimer's Disease: What It Is and What You Can Do. Chicago, IL: Alzheimer's Association, 2005. Available for download in PDF format at http://www.alz.org/national/documents/brochure_basicsofalz_low.pdf (accessed April 13, 2008).

Shenk, David. The Forgetting: Alzheimer's: Portrait of an Epidemic. New York: Doubleday, 2001.

PERIODICALS

Grady, Denise. “Finding Alzheimer's before a Mind Fails.” New York Times, December 26, 2007. Available online at http://www.nytimes.com/2007/12/26/health/26alzheimers.html?WT.mc_id=HE-D-I-NYT-MOD-MODM039-ROS-0408-L2&WT.mc_ev=click&ei=5087&en=8c097620f33e2092&ex=1223524800&mkt=HE-D-I-NYT-MOD-MOD-M039-ROS-0408-L2&pagewanted=all (accessed April 12, 2008).

Grady, Denise. “Reporter's File: Zen and the Art of Coping with Alzheimer's.” New York Times, April 14, 2008. Available online at http://health.nytimes.com/ref/health/healthguide/esn-alzheimers-ess.html (accessed April 15, 2008). Web page includes a slideshow of an artist with AD as well as two news videos about the disease.

“Study Confirms Imaging Compound Identifies Amyloid-beta in Human Brain.” Science Daily, March 13, 2007. Available online at http://www.sciencedaily.com/releases/2007/03/070312161151.htm (accessed April 14, 2008). This is a news report about the development of Pittsburgh Compound B.

WEB SITES

Alzheimer's Association (AA). Brain Tour. http://www.alz.org/brain/01.asp (accessed April 14, 2008). This is an interactive module with 17 sections, the first seven offering a basic introduction to the major parts and functions of the human brain, with the last 10 parts describing and explaining the stages of Alzheimer disease.

Public Broadcasting Service (PBS). The Forgetting: A Portrait of Alzheimer's. http://www.pbs.org/theforgetting/index.html (accessed April 12, 2008). This is the website of a television show about AD based on David Shenk's book and first aired in 2004. The site includes an interactive module about the symptoms of AD as well as a page with thumbnail biographies of famous people who died of Alzheimer disease.

UXL Encyclopedia of Diseases and Disorders

More From encyclopedia.com

About this article

Multiple: Alzheimer Disease

Updated About encyclopedia.com content Print Article

You Might Also Like