Centenarians - Balancing Genes and Environment

Robert W. Griffith, MD
October 15, 2004

Professor Thomas Perls of Harvard Medical School is the founder of the New England Centenarian Study (NECS); this study reports on the heath of some of the United States' oldest citizens. He has distilled the most interesting results in his book "Living to 100". Here is the 7th in our series of extracts from the book. Robert Griffith, Editor.

By 1998 we had discovered the R, P, and K families. The appearance of heritable longevity in these families was enough to persuade us that the most important difference by far in a person's ability to reach extreme old age was genetic. We had met centenarians who ate unhealthy food, and some who have even been smokers for a time. Furthermore, if genes exerted little protective effect, we would not expect to see centenarians who had a history of significant toxic exposures. Yet when we met Michael Makowski, the oldest man in Rhode Island, he told us that he had worked for years in a Pennsylvania coal mine and a Rhode Island shipbuilding foundry. Daily industrial poisons have not prevented him from reaching the age of 104.

As our studies progressed, the picture became clearer. Certain genes, it appeared, helped people age more slowly and keep their health long after most older people began developing chronic diseases of aging or died. The few genes that conferred this ability had such a marked life-extending effect that we were able to see the pattern of their inheritance through multiple generations of family members. In some cases, the effect of these genes was so strong that is allowed people like Mr Makowski to survive prolonged exposure to hazardous toxins.

We had to integrate our observations about centenarians and their families into an understanding of the interplay between genes and the environment. It was clear to us that even if a person was exposed to the worst of environments, the right combination of genes could still give the ability to achieve extreme old age. On the other hand, it would be very unlikely that a person without a minimum level of genetic advantage would be able to reach extreme old age, no matter how well that person controlled his or her environment.

We of course were eager to use [our results] as proof positive that we had found families in which longevity assurance genes existed. When he saw our data, [Cambridge geneticist Dr Leonid] Kruglyak cautioned against doing so. The study showed that there was a familial factor in aging, he said, but genetics were not the only forces at work in families. Under most circumstances siblings grow up together, go to school together, eat together, and share similar attitudes about life. Other longevity researchers would use that as a basis to dismiss our findings.

Of course we had considered the possibility that an important component of the ability to live to 100 lay in attitudes and personality. But there was nothing in our research to suggest that those effects would be limited to family members. In fact, the people who would be most likely to share our centenarians' lifelong habits and benefit from their example were not necessarily aging well. These were the centenarians' spouses. If a shared diet or shared attitudes were responsible for the sibling's longevity, we should have seen at least some statistical difference in the spouses' length of life. But there was no visible correlation between being the spouse of a centenarian and living to extreme old age. As a group, the spouses' life spans were just average.

The families we had discovered, along with the sibling pairs, indicate not only a powerful genetic influence on aging, but also the involvement of a relatively small number of genes. The existence of a few powerful aging genes, and the possibility for identifying them, opens the door to discovering how these genes exert their influence, and even to understanding how the process of aging occurs. [However], it was unclear to us how the ingredients of longevity-enabling genes would be transformed into a successful recipe for aging.

In 1981, Stanford University's James F. Fries proposed the hypothesis that healthier lifestyles, improved medical care, and higher standards of living would compress, rather than expand, morbidity. We had observed that most centenarians were healthy throughout most of their lives, that the vast majority remains healthy well into their nineties and sometimes into their hundreds, and that they frequently delayed chronic diseases of aging, if they hadn't avoided them completely. Almost none of our centenarians had suffered from life-threatening cancer. In fact, the only chronic disease we found commonly among centenarians was arthritis. A quick survey showed that, on average, our centenarians lived without disability until about age 97 and were taking an average of only one medication. When we asked families how long the deceased centenarian relatives had any form of disability before their deaths, their average answer was four years. This fit exactly with Fries' estimate that morbidity could be optimally compressed into 4% of the total lifespan.

If people want to emulate centenarians, they must imitate the centenarian ability to compress their period of morbidity into the last years of life. What centenarians do "automatically", we have to do "by hand". Therefore we urge people to look into their family histories, determine whether their ancestors lived beyond average life expectancy, find the causes of death and disability, and make intelligent choices about how they can delay or even prevent the diseases that killed or disabled their predecessors. We include specific information in Chapter 7 about how people can prevent chronic and disabling diseases of aging.

People with an optimal combination of genes that affect aging can probably afford to relax and indulge themselves a little bit. They can place some trust in their genes' ability to slow their aging. But those who have family histories of cancer, heart disease, Alzheimer's disease, diabetes, and other afflictions should begin doing what they can now to compress inevitable illness into a small percentage of what could possibly be a very long life.

As average life expectancy increases, all of us must begin making important choices for ourselves. Will people be able to compress the morbid periods of their lives, as centenarians do? Or will they end their lives in long periods of painful decline, the tendency we've seen among people who die in late middle age. If baby boomers want to avoid this fate, they must be prepared to use sensible measures to compress their period of chronic illness into the last few years of their lives.

In the next extracts from his book, Professor Perls looks at how would-be centenarians should order their lives to try to achieve their goal. You can buy his book "Living to 100" at Amazon; click here

Source

• Perls TT, Silver MH. Living to 100: Lessons in Living To Your Maximum Potential at Any Age. 1st edition, Basic Books, New York, NY, (1999).

Related Links
The Centenarians Study
The New England Centenarian Study
Low Diastolic Pressure and Alzheimer Disease in the Very Old
Preventing Cardiovascular Disease with One Pill?

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