Sept. 28, 2000 -- It is as much a philosophical question as a scientific one: How old can humans get? The evidence from a new study published in the journal Science suggests we have yet to find the answer.
The study shows the maximum life span increase in Sweden -- and by inference, other industrialized countries -- has continued to rise in the past century, but most especially during the past 30 years. From 1861 to 1969, maximum age at death in Sweden rose less than half a year per decade. Since then, the rate's more than doubled -- to 1.11 years per decade. The oldest Swedes now die at an average age of 108 -- eight years older than their counterparts from the 1860s.
The researchers hypothesized that there could be two explanations for this rise in maximum death-age. It could simply be that with more people in Sweden there is a greater likelihood of finding very old people. Or, it could be that the odds of surviving to an old age have gotten better -- that is, that death rates in old age have dropped. Their analysis determined that this second option was more likely the case than just simply attributing the rise to more people.
In any case, they say, their findings refute the popular notion that humans have a fixed life span over time -- and that survivability beyond the age of 70 is the major factor influencing the numbers.
Why use Sweden? The researchers say the Scandinavian country has kept the longest series of reliable information on national demographics, dating back to 1861. Their feeling is that death histories of other countries in Western Europe and North America are similarly reliable -- but available statistics did not go back as far as Sweden's.
"It's clear that people are living longer, and it's clear we can see no end with the improvement of life span," says Richard Suzman, PhD, associate director of Behavioral Social Research at the National Institute on Aging. "What accounts for the improvement in life span is a complex question that I don't think we have the full answer to. ... How much of it is related to medicine, public health, improved education, wealth, improved prenatal care, and early childhood conditions? I think all of these factors play a role, and we don't fully understand how to rank their importance."
He says what's perhaps more surprising than the improved longevity itself is the fact it hasn't been accompanied by an overall rise in health problems. "What everyone feared is that we would see an explosion of chronic disease and disability. [On the whole] we're not seeing that. We're seeing improvements in health at the same time we're seeing lengthening of life. The cautionary note is although people are making very significant advances in understanding, say, Alzheimer's disease -- it's still a chronic disease with enormous repercussions and consequences."
Bob Roush, EdD, MPH, of the Huffington Center on Aging at the Baylor College of Medicine in Houston, says preventing senility and frailty are two of the key challenges facing an aging population. "'Don't do me any favors making me live until 110 if I don't know what's happening at 98.' That's the conundrum," he says.
"My whole pitch on increasing the quality of one's geriatric life is not just for today's older people but tomorrow's older people," Roush tells WebMD. "[You can live well] by staying strong, taking the stairs instead of the elevator, keeping your cholesterol down, alcohol in moderation ... don't outlive your resources. Prepare for a long life -- physically and financially -- and don't forget the spiritual side of things. Plan on living for a long time -- because you probably will."