Ask Harriet MacGuinness of Bloomfield, Conn., how concerned she and her friends are about old-age afflictions striking down their independence.
``I think it's in the back of everybody's head,' says MacGuinness, who is 77.To die peacefully without suffering a long-term illness would be the best way for old age to end, she says. But ``most of us aren't going to be that lucky.'
A warning along those lines is contained in research on life expectancy published in the weekly journal Science. ``In fact,' say the researchers, S. Jay Olshansky, Bruce A. Carnes and Christine Cassel, ``we may be trading off a longer life for a prolonged period of frailty and dependency.
``It is not clear whether a longer life implies better health,' they say.
Even if cancer, heart disease and other major life-threatening illnesses are someday curable, it is highly unlikely that Americans' life expectancy will exceed age 85, they say. Life expectancy for those born in 1989 (the most recent projection available) is 75.
The report, by the three researchers at the University of Chicago and the Illinois-based Argonne National Laboratory, estimates that to increase American life expectancy to age 100 would ``require reductions in mortality of over 85 percent from present levels.'
Their results show that mortality rates for all causes of death would need to decline at all ages by 55 percent, and by 60 percent at ages 50 and older, for life expectancy at birth to increase from present levels.
The findings are in sharp contrast to the enormous gains in life expectancy achieved in the past 125 years, during which life expectancy at birth doubled from 40 years to almost 80 years, largely because of declines in neonatal, infant and maternal mortality.
Richard Suzman, a sociologist overseeing research on the 85-plus population for the National Institute on Aging in Bethesda, Md., says future forecasting of the size, distribution, health status and medical-care needs of the nation's elderly population will be affected by research that upsets prevailing projections.
Other researchers doing work for the institute do not agree with this newest report, Suzman says, calling it ``a scientific debate with important differences, and they will have to be solved by argument and debate and by doing new studies.'
One ongoing study for the institute, by Kenneth Manton of Duke University in Durham, has projected far greater life expectancy based on improved public health, new lifesaving technologies and a decrease in smoking and drinking, and it forecasted that people would commonly live well into their 90s.
Suzman, chief of demography and epidemiology in the behavioral and social research program of the institute, says of the many previous life expectancy forecasts, ``Most have proved wrong.'
Most often the life-expectancy cap has been underestimated. With ongoing studies, results remain to be seen, he says.