Researchers at Beth Israel Deaconess Medical Center in Boston say the secret of human longevity may be a group of genes they found on a single chromosome. They say those genes may actually slow the aging clock for those who possess it.
Dr. Thomas Perls, co-author of a new study on the subject, has been looking for hints by studying siblings who have prospered into their 90s under their own steam, without dependence on modern medicine.
The study will be published Tuesday in the Proceedings of the National Academy of Sciences.
"There was this idea that the older you get, the sicker you get," Perls said. "But you can't be a centenarian and get the diseases that many other older people get. (Centenarians) may have genes that allow them to escape disease and slow aging."
Perls' next step is to isolate the specific gene that is unique for people who live to extreme old age.
"We're not trying to find the fountain of youth," said Perls. "We're trying to find the fountain of aging well."
The differing lifestyles and unpredictable fates of older people have created a mystery for those seeking to understand what makes for a long life. Some seniors have kept meticulously healthy lives and then died in their 70s of natural causes. Others eat without caution, drink, smoke, never exercise, but live to 100.
At age 89, Joe Wilcox counts himself as proof that age is in the genes.
His uncle and aunt both lived into their 90s. His grandfather lived to 108. He loved bacon, cheese and salt.
"I didn't pay any particular attention to what I ate," said Wilcox, who has been retired for almost 20 years. "It can't have anything to do with diet. I used to eat hamburgers almost every day."
The end goal for researchers like Perls is to develop therapies that will help everyone slow the rate of aging, just as occurred naturally in the centenarians his group studied.
While that is a long way off, social scientists are already warning of new problems that would be caused by entire generations living longer.
"One of the principle strains on Social Security now is that people are living longer," said David Certner, director of economic issues for AARP.
"If people were to live even longer there would be a greater need to encourage people to invest money and plan on working longer. Workplace policies would also have to adapt to the changes, too, not pushing people out as they get older."
Therapies for the general populace would rely upon successfully isolating and understanding how the genes freeze the aging process, scientists say. The mystery is far from being solved.
Perls said the section of chromosome 4 isolated by the researchers contains 100 to 500 genes. It remains unclear which or how many of the genes affect life longevity. Perls said genes on other chromosomes alo may be involved by working in concert with the chromosome 4 genes.
The key chromosome section was found by studying the gene structure from 137 sibling groups that had demonstrated the family trait of long life. At least one member of each sibling group had reached the age of 100 or more, and the brother or sister had to be age 91 or more. The study group included 308 people with ages ranging from 91 to 109.
Blood samples were removed from each of the study subjects and their genetic structures compared to find genes that might relate to aging. This narrowed the search to chromosome 4.
Perls said it is possible that people who inherit the trait of living a century may have "the ideal human genome," or gene structure.
By Christopher Newton
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