Alzheimer's disease Health Article

Definition

Alzheimer's disease, or AD, is a progressive, incurable disease of the brain caused by the degeneration and eventual death of neurons (nerve cells) in several areas of the brain.

Description

Patients with AD first lose such mental functions as short-term memory and the ability to learn new things. In the later stages of AD they gradually lose control over their sense of orientation, their emotions, and other aspects of behavior. End-stage AD is characterized by loss of control of body functions, an increased likelihood of seizures, loss of the ability to eat or swallow, and eventual death from infection or malnutrition. Alzheimer's disease is the most common cause of dementia (loss of cognitive abilities) in the elderly; it is thought to be responsible for 50%–70% of cases of dementia in the United States.

Alzheimer's disease was first identified in 1906 by a German psychiatrist and neuroanatomist named Alois Alzheimer. He was studying slides prepared from the brain of a fifty-one-year-old woman, known as Frau D., who had died after several years of dementia with symptoms that did not fit the definition of any brain disorder known at the time. Alzheimer was the first to describe the plaques and neurofibrillary tangles that are now used to identify AD at autopsy. Plaques are clumps or clusters of dead or dying nerve cells and other cellular debris found in the brains of patients with Alzheimer's disease. Neurofibrillary tangles are the accumulations of twisted protein fragments found inside the nerve cells in the brains of Alzheimer's patients. Because dementia had been associated with elderly people and Frau D. had been middle-aged, AD was first known as presenile dementia and was thought to be a very rare disorder. It was not until the early 1950s that researchers at St. Elizabeth's Hospital in Washington, DC, came to recognize that AD is the single most common cause of dementia in adults.

Alzheimer's disease is now considered a very serious public health problem because of the growing numbers of people who are affected by it, the increasing length of their lives, and the direct and indirect costs of their care. It is estimated that four million people in the United States had AD as of 2000, with 360,000–400,000 new cases identified every year. One person in ten over the age of 65 has AD, and nearly 50% of those over 85 have the disease. Unless a cure or preventive treatment is discovered, 14 million Americans will have Alzheimer's by 2050. Very few people are wealthy enough to cover the cost of caring for an Alzheimer's patient in the seven–10 years that typically extend between the beginning of the person's dependency and death. The average lifetime cost of caring for one patient with AD is estimated at $174,000. The costs of laboratory tests, physicians' visits, medications, nursing services, home care, and adult day care come to $114.4 billion per year in the United States alone. This sum is greater than the combined annual budgets of six Federal departments (Commerce, Education, Justice, Labor, Energy, and Interior).

The problem is expected to be complicated in future years by the fact that the so-called "baby boomer" generation is better nourished and better educated than the generation now at risk for AD. When the baby boomers are old enough to be at risk for late-onset Alzheimer's, they are expected to live longer than the average Alzheimer's patient does in 2002. Public health researchers who are making future projections about the impact of AD in the mid-twenty-first century point out that a treatment that would delay the onset of the disease would reduce the overall prevalence of AD. One study estimates that a therapy that would delay the onset of Alzheimer's by only one year would save the United States $9 billion by 2007. The second approach, that of discovering a treatment for people who already have Alzheimer's, would alter the proportion of mild cases to those considered moderate or severe. The researchers conclude by stating: "None of our models predicts less than a threefold rise in the total number of persons with Alzheimer's disease between 2000 and 2050."