Alzheimer

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

beyond the effects of normal aging. It is named for Alois Alzheimer

(1864

disease at a medical meeting in 1906.

the loss of a person’s memory and other cognitive functions–1915), a German doctor who first described a patient with the

Description

AD affects a person

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

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

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.

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

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

developing AD include:

–5 percent of cases, however. Most cases of Alzheimer’s are considered’s risk of

•

High blood pressure or high blood cholesterol levels

•

Heart disease or stroke

•

Head injury

•

Diabetes

•

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:

Female sex

•

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.

Mild cognitive impairment. This phase can begin as long as eight

•

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.

Early dementia. The person begins to have language problems as

•

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.

Moderate dementia. The person loses the ability to live independently

•

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:

•

to rule out infections or heart problems that might affect memory

and other cognitive functions.

Laboratory tests of blood and urine samples. These tests are done

•

rule out brain tumors, Parkinson disease, infections of the brain, or

stroke.

Imaging studies, usually an MRI or a CT scan. These are done to

•

person

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.

Mental status examination (MSE). This type of test evaluates the’s awareness of their location in time and place; their ability

•

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.

A PiB PET scan. PiB stands for Pittsburgh Compound B, a chemical

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 lateonset

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 diseaseAdvanced dementia. The person loses the ability to talk except for—14 percent of the population over’s’s ability to think clearly, to remember, to speak, to

Alzheimer Disease