The number of people with Alzheimer's disease will triple by 2020 as the baby-boom generation approaches the peak years for getting the degenerative mental condition, researchers said yesterday.
Dr. Claudia Kawas, an associate professor of neurology at the Johns Hopkins School of Medicine, said there will be 14 million Americans with Alzheimer's 2 1/2 decades from now -- compared with 4 million today.
Not only will the post-World War II generation constitute the largest population of senior citizens in U.S. history, but medical advances are allowing people to live longer. With longevity comes a price: a greater likelihood of getting Alzheimer's, a brain disease that depletes memory, reasoning and the ability to bathe, dress and even feed oneself.
"The risk of getting Alzheimer's doubles with every five years of age," Dr. Kawas said during a forum at the week-long convention of the American Association for the Advancement of Science, which ended yesterday. Peak years for developing Alzheimer's are 80 to 85.
The trend is likely to place unprecedented demands on the health care system, principally for nursing and custodial care. And because baby boomers are having fewer children than their parents did, the burden on today's youngsters could be great.
But Dr. Kawas and others speaking at the Alzheimer's session said advances in understanding the disease may make it possible to identify people at risk and either postpone the onset of symptoms or ease them once they occur. Drugs now being tested might also be used to manage the disease, just as different medications are now used to manage stroke and heart disease.
Researchers are also beginning to see subtle changes -- such as lower scores on visual memory tests -- that occur many years before classic symptoms of Alzheimer's appear. This could make it possible to intervene with drug therapies 10 or even 20 years before the state that is now recognized as the onset of the disease.
In recent years, researchers have identified four genes that place people at higher risk for Alzheimer's, but none guarantees it. In studies of identical twins, researchers found that one twin had a 40 percent chance of getting the disease if the other already had it.
Individual risk factors have been shown to raise the chances of getting the disease. These include a family history of Alzheimer's, past incidents of head trauma, coronary artery disease and, possibly, being female.
More women get the disease than do men, but the reason is unclear. One explanation is simple: Women survive longer. But hormonal differences may place women at higher risk, Dr. Kawas said.
Some studies seem to suggest that women who take estrogen replacement drugs after menopause also lower their risk of getting Alzheimer's, she said.
Dr. Christopher Ross, an associate professor of psychiatry at Hopkins, said physicians have the tools to treat the emotional symptoms that afflict many patients with Alzheimer's -- the same drugs that are used to treat depression and other psychological symptoms in younger people.
"Unfortunately, this is a devastating and tragic disease," he said. "We can't do much about the course of the disease, but we do have treatments for the emotional symptoms."
Alzheimer's victims often become depressed before they suffer other symptoms. For this reason, emotional disturbances are often the initial reason that patients are admitted to nursing homes.
"We can postpone some nursing home placements" with appropriate use of anti-depressants and other drugs that alter mood, Dr. Ross said.
Depression, which afflicts 38 percent of Alzheimer's patients, is not simply despair over the loss of capacity. Two-thirds of Alzheimer's patients who develop depression have a family history of the mood disorder -- an indication that these patients are genetically predisposed to become depressed.
"The biological changes of Alzheimer's disease brought it out," Dr. Ross said. In contrast, only about 5 percent of the patients who develop depression have no family history whatsoever.
Once depression is eased, an Alzheimer's patient can often live without feeling disturbed about the loss of function, he said.
"Lots of people with Alzheimer's disease are really quite cheerful," he said. "Alzheimer's disease not only interferes with memory but the ability to appreciate their own disability."