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A GOOD AGE; Healthy Lifestyle Helps Many Reach 100

Posted on: Wednesday, 30 June 2004, 06:00 CDT

Sue Scheible

What does it take to become a centenarian?

Whenever I interview or read about someone who is 100 or older, I look for clues to why they live so long.

Usually they are not only very old, they are also surprisingly healthy for their age or remarkable in another way. What accounts for their good fortune? Is it just that, luck? Genes? A certain attitude or lifestyle? It is some of each, although more lifestyle than genes, says a recent report by the International Longevity Center-USA and the AARP Foundation.

"Longevity Genes: Hunting for the secrets of the centenarians" says that genes account for 30 percent of our longevity. The other 70 percent is attributed to sensible habits and lifestyle: a nutritious diet, moderate exercise, not smoking, moderate alcohol intake. The physical and emotional benefits of those lifestyle factors have been well documented. Certain personality traits such as optimism, flexibility and humor also have been linked to longer life.

A good example is Priscilla Call of Pembroke who turned 100 June 16. The Ledger reporter who interviewed her wrote, "Although small in stature, Call commands attention with her wit, personality and storytelling skills. She is quick with a comeback." With a wry smile, Call said, "I haven't lost my buttons." In her life, she has shown the ability to adapt to change. After asking her first husband for a divorce, she created an independent lifestyle, later remarried and worked until age 81.

The average American's life expectancy has risen to 77.2 years - an increase of more than 30 years over the last century. There are 50,000 centenarians in the United States, according to the latest census.

Why has such a boost in longevity taken place? The public health campaigns (sanitary drinking water, immunizations, antibiotics) of the early and mid-20th century played a big part, as did medical advances that help people survive heart disease, cancer and other illnesses that are more common with age. Several new drugs to lower high blood pressure and cholesterol have saved or extended lives.

In the Nun Study, David Snowdon followed 678 nuns, aged 75 to 106. He concluded that a basic optimism early in life and richly expressed positive emotions may increase longevity. The New England Centenarian Study, led by Dr. Thomas Perls, suggested a stress- resisting mindset and lifelong learning may enhance aging.

Now genes are the exciting new angle. Certain genes allow some people to cope better with stress, react better to hormones and regulate how fast we age, according to ongoing studies.

We already knew that estrogen protects women during aging in ways that men don't enjoy. This latest explains why some women have an extra advantage and live longer than others.

Many kinds of genes influence how we age. They control when our hair turns gray or if we are likely to get osteoporosis or arthritis.

But they don't control how long we live.

Researchers are looking for specific "longevity genes," according to Dr. Robert N. Butler, president of the International Longevity Center-USA in New York.

In the new booklet, Butler explains how scientists are identifying which genes are present in centenarians. An individual has 23 pairs of chromosomes that hold 30,000 genes. The analysis looks at how many genes someone has and how they are arranged. The goal is to identify genetic "lottery winners."

Very simple organisms such as worms, fruit flies and mice hold some keys. Scientists are finding genes that influence how the tiny organisms react to stress and to certain hormones. These genes may also regulate proteins that repair or prevent damage to cells and so delay the rate of aging. For example, if certain genes are mutated or changed, the C. elegans roundworm's life span increases. That is because the changes improve the worm's resistance to stress, lower its metabolism rate or weaken an insulin-like hormone that can be damaging.

Of course, there is no guarantee humans react the same as these very simple organisms. But fruit flies and worms have short, predictable life spans and a clear genetic makeup, so scientists can study many generations and draw conclusions. And there are similarities at the cellular and molecular level between worms and humans. Scientists also located a "methuselah" gene in fruit flies that boosted the resistance to stress and they created a mutant gene they named INDY (I'm Not Dead Yet) that doubled the fruit flies' life span.

Mice have yielded other clues. There is a very small mutant mouse, called the Snell dwarf, that has less growth hormone and lives longer than other mice. The Snell mice are slower to show old age characteristics and slower to develop arthritis. And there's also calorie restriction: By limiting the caloric intake, scientists extended the lives of the Snell mice even longer.

There are four theories about why mice live longer when fed low- calorie diets. Much of the aging process is due to byproducts of metabolism called free radicals, produced when cells use oxygen. One theory is that calorie restriction lowers this oxidative damage to cells by slowing metabolism. Another theory: the restriction may reduce blood glucose, also linked to a biochemical aging process. A third theory is that using fewer calories lowers body temperature and cells then sustain less damage. Finally, calorie restriction may slow disease by keeping the immune system "young." As to what all this means for humans, the jury is still out. But it has been shown that mice fed low-calorie diets with essential nutrients live as much as 30 to 40 percent longer.

So far, there's no "magic bullet" gene, and a healthy lifestyle still has much more of an influence on longevity. But the genetic possibilities are intriguing. For a copy of the publication, "Longevity Genes: Hunting for the secrets of the centenarians," call 212-606-3383 or visit www.ilcusa.org.

MEDICAL BROCHURES - The Massachusetts Medical Society has several free brochures for seniors and their caregivers. "Simple Measures for Successful Aging" offers tips on sleep, exercise, nutrition and common sense prevention activities. "Keep Moving" focuses on physical activity, including flexibility, strength, balance and endurance. "Saving a Million Memories" encourages patients to look for the early warning signs of memory disorders and has tips on how to get the most out of a visit to a doctor.

A fourth brochure, "Healthy Mind, Healthy Body" will have tips for keeping the brain active and is due out soon. For a single free printed copy of each of the brochures, call 1-800-843-6356. The brochures also are available online at www.massmed.org/pages/ geri_about.asp.

Reporter Sue Scheible can be reached at 617-786-7044, by mail at The Patriot Ledger, Box 699159, Quincy, MA 02269-9159 or E-mail at sscheible@ledger.com.

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