Date: July 1st, 2004
If you could swallow a little yellow pill and live to be 120 years old, would you? Would your good health hold out that long? Would your retirement savings last for 50 years? Could society sustain an explosion of "super seniors"?
The benefits and consequences of scientific breakthroughs in life extension were debated at a medical conference in Newark, NJ in April entitled, "Creating Very Old People: Individual Blessing? Or Societal Disaster?" While there is no magic bullet, no little yellow pill available to extend life, the conference hosts and speakers unanimously agreed that with emerging technologies, the human life span will indeed lengthen-it's just a question of when.
"This is inevitable; there is no turning back," said Dr. Donald Louria, professor of preventive medicine at the University of Medicine & Dentistry of New Jersey and conference organizer. Today's life span is approximately 77 years. Dr. Louria predicts that by the end of this century, the average life span at birth will be 95 to 99 years. Shortly thereafter, we'll reach the 110 to 120 year mark and beyond. Eventually, there may be no upper age limit once scientists learn to control the aging process.
The desire to prevent or slow aging and delay the inevitability of death is universal and scientists throughout history have explored the aging process to learn its secrets. Many secrets are being revealed with exciting technological advances, each with the expectation that some day new drugs will buy us more time on earth.
Caloric restriction (CR), or limiting food intake by 30-40 percent, has shown promising results in animal studies, according to Dr. George Roth, a senior guest scientist at the National Institute on Aging and CEO of Geroscience. When animals are fed less food, they live longer, stay healthier, and maintain better functioning than animals that eat an unrestricted diet. CR slows the rate of energy flow so there is less wear and tear on the body and boosts protective mechanisms that work against damaging forces, such as ultraviolet light and free-radicals.
Scientists are now working to create pharmaceutical CR mimetics that influence the three biological markers of longevity. In animal studies, the monkeys with a lower serum level of insulin, a lower body temperature, and a better ability to maintain the level of the hormone DHEA lived longer than other test subjects. "The three markers of longevity worked independently of caloric restriction," Dr. Roth said. "Knowing that, we felt that if we could find a way to get a lower level of insulin, lower body temperature, or a higher level of DHEA by a CR mimic, then we would get the same beneficial effects in terms of longevity and health maintenance without restricting food intake."
Many companies are now marketing dietary supplements that claim to increase longevity, including Melatonin, SAMe, and Resveratrol, but none have been validated in animal studies to provide even 50 percent of the beneficial effects of caloric restriction, Dr. Roth said. And, he noted, none have been proven to prolong longevity in humans.
In another area of aging studies, telomeres are considered to be a biological time clock that determines maximum life span. Telomeres are structures at the end of chromosomes that shorten each time a cell divides. When telomeres become too short, the cell can no longer replicate and therefore dies. Researchers are studying the conditions under which telomeres appear at different lengths, and substances that may effectively lengthen telomeres to increase cell life. Excess weight has been linked with shorter telomeres.
When scientists identify genetic variations that influence aging, these models of genetic differences can be used to create drugs to manipulate the aging process. Dr. Richard Miller, associate director of the Geriatrics Center at the University of Michigan, uses the mouse model to find genes that affect the functioning of mice when they get old. Changes in single genes can lead to a 50 percent increase in life span. The Snell dwarf mutation in mice can slow aging of the eyes, immune system, brain, and skin, as well as cancer development. Once genes are identified, their proteins can be characterized, and new pharmaceutical products can be developed.
Older adults over age 85 represent the fastest growing segment of the adult population, with a current 4.5 million in this age group in the U.S. By 2050, it is estimated there will be 20 million people over age 85-that is, without interfering with the aging process. If scientific progress successfully slows aging allowing more people to live longer, the implications for our society could be significant.
If people live to age 115, yet still retire at age 60 to 70, they will spend 40 to 50 years in retirement instead of the current 20 years. Social Security and employer pensions will likely be insufficient when there are only two workers for every retiree, as projected in 2050. In addition, if older adults ages 65 and beyond decide to return to the workforce after retirement, four generations of people could be competing for the same job, Dr. Louria said.
Dr. Louria also states, as science moves inexorably toward the future, our society must become prepared by looking at the long-term effects of life extension through epidemiological studies and public debates on the quality of life issues.
"The goal of the conference was to get people to realize that this is our demographic destiny," he said. "We have to think about this issue and decide how we can best handle what is almost inevitable. What is clear is that we cannot wait until it happens and then we'll muddle through. That is a recipe for disaster."