By LEE BOWMAN
Scripps Howard News Service
February 17, 2006
Aubrey de Grey, a gerontologist at the University of Cambridge, England, told the American Association for the Advancement of Science on Friday that he feels science needs to make a more coordinated push toward anti-aging medicine.
He compared his approach to restoring storm damage to a house. "This means that an individual who is already middle-aged or even older can in principle be restored ... to a biologically more youthful state."
The researcher said he feels there's a 50 percent chance that, within the next two decades, scientists could develop a line of therapies that would give middle-aged people an extra 25 years of healthy life. "Making 80 like 60 is a reasonable goal, but extending lifespan is really only a side effect to therapies that keep people healthy and robust as they grow older."
These would include stem-cell therapy and injection of growth factors, gene therapy and immune-system therapy.
The researcher said it's unlikely therapies can fix all the damage of aging, "but that's not necessary, because we know our tissues can cope with modest amounts of these types of damage, because that's what exists in young to middle-aged adults, whose bodies are working fine."
Steven Austad, a researcher at the University of Texas Health Sciences Center in San Antonio, agreed that animal experiments have been "wildly successful" at extending lifespan, and that some of those therapies could transfer to humans.
"But some of the downsides of these interventions haven't been as widely reported. There's evidence that the approaches that involve cutting calorie intake and genetic modification can affect fertility, susceptibility to cold, and hurt the ability of the immune system to respond to infections.
"You have to ask: What's the point of extending lifespan if you're more likely to die from the flu?" He added that he thinks that, in the near future, medicine will continue to extend lifespan in the same way it has for the past several decades, by finding better ways to treat disease.
But what happens if people do start living longer?
Stanford University biologist Shripad Tuljapurkar worked with an assumption that the most common age of death would increase by 20 years between 2010 and 2030. Such a projected increase reflects a lifespan growth rate that is five times faster than the current rate, increasing the anticipated lifespan in industrialized countries from about 80 years to 100.
Even though the trend wouldn't extend equally around the globe, "one thing that happens right away, which nobody seems to have thought of, is that the total global population increases dramatically," Tuljapurkar said.
"From an original projection of 8 billion people (in 2030) we end up topping out at 10 to 11 billion. China and India alone would add half a billion people between them."
On the other hand, a longer-lived population could have a positive effect for countries with low fertility rates. "Countries like Sweden and Italy have been having this huge debate for many years over population decline," Tuljapurkar said, with economists warning that only increased immigration will keep national economies going.
In the United States, Tuljapurkar calculated that if centenarians become commonplace, it could drastically increase the ratio of people of working age - 20 to 65 - to people over 65 whose Social Security and Medicare benefits are sustained by taxes paid by those working.
Already, this dependency ratio is expected to double to two retirees for every five workers by 2035; but if another 20 years is added to lifespan, that could push the ratio to 4 for 5. "The retirement age would have to go to 85 for things to balance out financially," he said.
Of course, if people know they're going to live longer and healthier, presumably the working lives of many Americans would also be stretched out - a trend already taking hold in many parts of the labor market, several speakers said.
"With the decline in fertility that this country has seen over the past century, we've already gone from a mostly youthful country to an older nation," said Eileen Crimmins, a demographer from the University of Southern California in Los Angeles. "We've made adjustments to the way we live accordingly, like our patterns of marriage (delayed) and divorce (more frequent). So there's no reason to think our society couldn't adjust to still more people living longer."
Tuljapurkar said individuals will need to prepare for living longer, too, educating themselves for one career, perhaps, but also setting a foundation to make it easier to go to a new line of work in their 60s or 70s and taking different approaches to retirement savings. "You've got an extra 20 or 30 years coming, the money's got to come from somewhere."
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