Alzheimer’s is the most common cause of dementia (artery disease, Parkinsons and other
brain disorders can also lead to dementia). Five million people in the United States have
Alzheimer’s, most of them over 65. It is the nation’s sixth leading cause of death by disease,
killing nearly 66,000 people a year and probably contributing to many more deaths. By 2050,
according to the Alzheimer’s Association, 11 million to 16 million Americans will have the disease.
“Sixteen million is a future we can’t countenance,” said William H. Thies, the association’s vice
president for medical and scientific relations. “It will bankrupt our health care system.”

The costs are already enormous, $148 billion a year — more than three times the cost of chronic

lung disease even though Alzheimer’s kills only half as many people. To a great extent, increases in dementia are the price of progress: more and more people are living long enough to get Alzheimer’s, some because they survived heart disease, strokes or cancer. It is a cruel trade-off. The disease is by no means inevitable, but among people 85 and older, about 40 percent develop Alzheimer’s and spend their so-called golden years in a thicket of confusion ultimately becoming incontinent, mute, bedridden or forced to use a wheelchair and completely dependent on others. “Alzheimer’s disease may be a chronic condition in which changes begin in midlife or even earlier,” said Dr. John C. Morris, director of the Alzheimer’s Disease Research Center at Washington University in St. Louis.

But currently, the diagnosis is not made until symptoms develop, and by then it may already be too late to rescue the brain. Drugs now in use temporarily ease symptoms for some, but cannot halt the underlying disease.

Many scientists believe the best hope of progress, maybe the only hope, lies in detecting the disease early and devising treatments to stop it before brain damage becomes extensive. Better still, they would like to intervene even sooner, by identifying risk factors and treating people preventively — the same strategy that has markedly lowered death rates from heart disease, stroke and some cancers.