The rapid growth in the number of centenarians in the United States - roughly a doubling every decade - is forcing society to reexamine what it believes about aging.
Researchers are already documenting that advancing years - even after 100 - can be more productive and independent than previously believed.
Their findings suggest potentially huge changes ahead:
*Retiring at 65 may be too young for tomorrow's elderly.
*Increasing health and longer productivity of the elderly may offset somewhat the economic burden that planners have long assumed for a graying America.
*Society's dismal view of old age may get a radical push toward the positive.
"We want to show aging is a light at the end of a tunnel rather than some kind of abyss," says Tom Perls, director of the New England Centenarian Study at Harvard Medical School and author of a new book, "Living to 100."
"Decades of research clearly debunk the myth that to be old in America is to be sick and frail," write John Rowe and Robert Kahn in their 1998 book "Successful Aging." "Our main message is that we can have a dramatic impact on our own success or failure in aging."
Some practitioners go much further than this. They predict medical breakthroughs will allow people to achieve a quasi-immortality by the middle of the next century. "When I talk about immortality, I'm not talking about living forever," says Ronald Klatz, a medical futurist and president of the American Academy of Anti-Aging Medicine in Chicago. "I am talking about life spans of 200, 250 years and more."
Such predictions are beginning to gain currency in the medical community as researchers discover genes that dramatically lengthen the life of some fruit flies and material called telomerase that increases the life spans of human cells.
But many mainstream gerontologists caution against forecasts of a human longevity boom, calling them wild guesses.
Even without dramatic breakthroughs in life expectancy (which in the US stands at just over 76), many people can lengthen their productive years significantly, these researchers say. By focusing on the healthy elderly - rather than the diseases of aging - they hope to unlock the secrets of a good long life.
The growing ranks of centenarians give them an important database for study. The US Census Bureau estimates some 66,000 Americans have crossed the century mark - nearly double the 37,306 it counted in 1990 and 15 times the number in 1950.
By the middle of the next century, the US could have 834,000 centenarians, according to the Census Bureau's middle-of-the-road projection.
The Census Bureau admits the true numbers of centenarians may be lower - perhaps closer to 50,000 today - because of persistent problems getting an accurate count. Still, the numbers reflect dramatic growth.
"Centenarians will become much less unusual and much more commonplace," predicts Kenneth Manton, director of the Center for Demographic Studies at Duke University in Durham, N.C. It's entirely conceivable someone will reach 130 in the next few decades, he adds, handily beating the official record currently held by Frenchwoman Jeanne Calment, who passed away two years ago at 122.
Debunking myths of aging
Scientific findings are already breaking down myths about the elderly. For instance:
* Old means sick. This theory is losing favor, according to the authors of "Successful Aging." Drawing on research from a MacArthur Foundation study on aging, and other sources, they found that a substantial majority of Americans into their mid-80s reported no disability. And even after age 85, 4 out of 10 reported they were fully functional.
*Advancing age means dependency. Only 5.2 percent of Americans 65 and over live in nursing homes - and that percentage is dropping, point out Dr. Rowe and Professor Kahn. Even among centenarians, independent living is not unheard of.
According to a study on centenarians based on the 1990 census and released earlier this month, nearly 1 in 5 could take care of themselves and move about freely; nearly 1 in 6 lived alone.
*Poverty is inevitable. Even among centenarians, researchers have found the full range of economic circumstance - from low income to vast wealth. The Census study found that three-quarters of centenarians in 1990 did not live in poverty.
*Mental acuity declines with age. Not inevitably, researchers say.
And experiments in the MacArthur study found that with training, older people could improve cognitive functions and short-term memory.
*Death is genetically programmed. At least through their 80s, researchers say, people's environment and lifestyle play a crucial role in how quickly they age physically and mentally.
They list factors ranging from avoiding cigarettes to physical exercise to a positive outlook. There is also evidence that a belief in God plays a role, they say.
Centenarians represent a special subgroup of the elderly, and they retain their own remarkable characteristics.
Centenarians are healthier
For example, as a group they're actually healthier than people in their 80s. And they spend less on hospital care than those in their 70s. When Perls and his colleagues at the New England Centenarian Study looked at Massachusetts hospital discharges for 1992 and 1993, for example, they found that the average cost of a hospital stay was highest for patients in their 70s, totaling $7,590 per discharge. For centenarians, it actually fell to $5,489 - a 30 percent decrease.
One reason is that "youngsters" in their 70s and 80s often receive expensive treatments that centenarians either don't demand or receive.
But the biggest reason seems to be that centenarians are simply healthier, Perls argues. Most of them don't survive disease, they avoid it completely.
And, contrary to what seems to hold true for those in their 70s and 80s, their longevity doesn't stem from their diet. Perls found some centenarians who eat little red meat, others who consume it every day. One centenarian in his study had been sitting down to a three-egg and bacon breakfast every day for the past 15 years.
Perls theorizes that the paradox may stem from genetic "booster rockets" that allow some people to blast past the century mark no matter what they eat. But centenarians also share a positive mental outlook, many researchers add, that may play an important role as well.
The new research could also become a self-fulfilling prophecy, researchers suggest. As people expect to live longer and in better health, they will take the measures necessary to achieve it.
"If they think that at age 82, 84, 85, they could be out there and still be pretty functional, then that's a whole different story," says Mr. Manton. "Then extending life further has meaning - not only for individuals but also for society."