WASHINGTON — WASHINGTON -- The common assumption that old age in the United States brings with it unremitting deterioration is being challenged by a new study that shows disability rates among the elderly decreasing during the 1980s.
Findings by three Duke University researchers -- Kenneth G. Manton, Larry S. Corder and Eric Stallard -- being published in the forthcoming issue of the Journal of Gerontology, have generated a whirlwind of discussion.
While many researchers said they were waiting to see the work duplicated by other demographers, they also said that the shift makes sense, particularly in light of the increase in commonplace surgical techniques -- like cataract removal and joint replacement -- that allow older people to resume the normal activities of daily life.
Another factor in the decline in disability rates may be the higher educational levels of those now entering retirement. Several studies, including those by a University of Pennsylvania sociologist, Samuel Preston, have found that higher levels of education go hand in hand with higher incomes, which are associated with better nutrition and health care.
"Education has lifelong implications, from having access to medical care to likelihood that you will take good care of yourself throughout your life," said Cynthia Taeuber, a demographer specializing in the elderly for the U.S. Census Bureau.
Eileen Crimmins, a professor of gerontology at the University of Southern California, said that while it would be important to replicate the Manton group's findings, there is an emerging belief that the idea of old age as a time of steady deterioration should be replaced by the notion that the health of old people, like that of young people, goes through phases, for better or worse.
"Now more and more people believe there's an ongoing change in both directions," she said. "Sometimes people get better, sometimes worse. Some things can get better while others get worse."
The Manton study showed that while the population of those past their 65th birthday increased by 14.7 percent between 1982 and 1989 -- from 26.9 million to 30.9 million -- the chronically disabled elderly population increased by just 9.2 percent.
Overall, the proportion of the elderly population reporting no disabilities rose from 76.3 percent in 1982 to 77.4 percent in 1989.
The new findings, which have been circulated in academic forums for more than a year, have obvious relevance to the discussions under way in President Clinton's Task Force on National Health Care Reform, several experts said.
"Manton's research findings are quite germane to the question of how many Americans will need long-term care in the future," said Alan Garber, an associate professor of medicine and economics at Stanford University.
Until recently, he said, it was assumed that elderly people whose lives were prolonged by medical intervention would live longer but that the extra time would mostly be spent in a disabled and dependent state.
Mr. Garber and others say the Manton study modifies that thinking somewhat. As baby boomers age, Mr. Garber said, "no matter what, we'll need more long-term care." But lower disability rates among the elderly may slow the increase in demand for costly nursing home care.