What is Alzheimer's disease?

Alzheimer's disease is a degenerative brain disorder that results in memory loss, impaired thinking, difficulty finding the right word when speaking, and personality changes (see "Warning signs of Alzheimer's disease," below). Its course is marked by a continual loss of neurons (nerve cells) in areas of the brain that are crucial to memory and other mental functions. Levels of brain chemicals known as neurotransmitters, which carry complex messages back and forth among billions of nerve cells, are also diminished. After the symptoms first appear, people live anywhere from 2–20 years in an increasingly dependent state that exacts a staggering emotional, physical, and economic toll on families.

There is no cure or even a firm cause or proven means of prevention. But early diagnosis is important because drugs are available that may temporarily stabilize or delay worsening of cognitive symptoms, and they work best in the early stages of the disease.

Warning signs of Alzheimer's disease

Trouble remembering things. At first, only short-term memory may be affected. The individual may forget an appointment or the name of a new acquaintance. She may also forget where she left things, or she may leave things in odd places (for example, putting her shoes in the microwave). Eventually, long-term memory also is impaired, and the individual may not recognize family members.

Mood or personality changes. The person may suddenly become angry or sad for no apparent reason. Or someone who was social and outgoing may become withdrawn. The person may also become stubborn or distrustful. Depression also often accompanies Alzheimer's disease, bringing such symptoms as loss of interest in a favorite hobby or activity, a change in appetite, insomnia or sleeping too much, lack of energy, and hopelessness.

Trouble completing ordinary tasks. Simple tasks that once caused no difficulty may become much more challenging. For example, the individual may forget how to use the oven, lock the door, or get dressed.

Difficulty expressing thoughts. It's common for people with Alzheimer's disease to have trouble with language. The individual may try describing an object rather than using its name — for example, referring to the telephone as "the ringer" or "that thing I call people with." Reading or writing may also be impaired.

Impaired judgment. The individual might have trouble making decisions, solving problems, or planning. For example, he may no longer be able to balance a checkbook or pay bills.

Disorientation. We all know what it's like to be driving and momentarily forget where we're going. But those with Alzheimer's disease may get lost in their own neighborhood. They may also lose track of dates and the time.

Unusual behavior. The individual may wander, become agitated, hide things, wear too few or too many clothes, become overly suspicious, engage in unsafe behaviors, or use foul language.

Reasons for hope

Nevertheless, there are reasons for hope. Promising results of broad-based brain research have made Alzheimer's researchers optimistic about the prospects for improved treatment and prevention. Intense efforts since the 1980s have advanced scientists' understanding of the chemical changes that take place inside the brain. Key discoveries have cleared the way for pharmaceutical companies to start developing compounds that might block the disease's destructive course and cure the patient. There is also hope that scientists will someday create a vaccine to prevent and even treat Alzheimer's disease (see "Alzheimer's disease vaccine").

These prospects are exciting, but they're still a long way from providing relief for the estimated 24 million people worldwide who currently have Alzheimer's disease. The good news is that science has given health care providers a better understanding of ways to improve the day-to-day lives of people with Alzheimer's. And this growing awareness has produced an increasing number of support groups and community services around the country to alleviate families' isolation and help ease the burden of caring for those with Alzheimer's disease at home.

A surprising history

The medical profession used to consider Alzheimer's disease a rare disorder that struck in middle age. This assumption was based on a report published in 1907 by a German doctor named Alois Alzheimer. During an autopsy, Alzheimer discovered microscopic changes — including abnormal neurons, tangled fibers, and clusters of nerve endings — in the brain of a 51-year-old patient who had died of progressive dementia. The report attracted attention within the medical community, and thereafter, progressive dementia in a person younger than 65 was called "Alzheimer's disease."

Doctors used to believe dementia in people over age 65 was caused by cerebral atherosclerosis ("hardening" of the brain's arteries), and it was labeled "senile dementia." (Senile simply means "old," and dementia is literally "deprived of mind.") But attitudes began to change in the 1970s. Evidence accumulating from autopsy studies suggested that Alzheimer's disease was, in fact, the most common cause of dementia in older persons. Because people were living longer, health professionals and elected officials alike were paying more attention to the problems of the elderly population. As a result, the National Institute on Aging was established in 1974, with one of its primary goals to conduct and support research on memory loss.

With the 1984 publication of diagnostic criteria for Alzheimer's and other irreversible dementias, physicians began diagnosing the disease more frequently. Meanwhile, the Alzheimer's Association, founded in 1979, began raising public awareness about the disease.

The growing numbers

Alzheimer's disease is most common among people ages 65 and older, and the risk rises steadily with age. In the United States, Alzheimer's affects 40% of the population age 85 and older.

Of course, Alzheimer's affects a far greater number of people, for it takes a toll on loved ones as well as those with the disease. With the graying of America, Alzheimer's disease is a growing national problem. Today, an estimated 4.5 million Americans have Alzheimer's. If no effective treatment or means of prevention is found, an estimated 13 million Americans may have Alzheimer's disease by 2050 — three times the figure today.

Most people with Alzheimer's disease are cared for at home by spouses or other family members, often for 10 years or longer. In many cases, this results in financial as well as emotional strain. For a person with Alzheimer's disease, the annual cost of home care is estimated at $76,000, including medical expenses and indirect costs such as a caregiver's time and lost wages. The resulting social burden is high. The estimated yearly cost to society for Alzheimer's disease is about $100 billion, which includes both direct and indirect costs.

Review Date: 2007-01-01

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