Key to longevity is still a mystery

Genes, lifestyle and luck all play a part in how long we live

November 15, 2007|By Susan Brink

Bill Walker's mother lived to 101, his Uncle Rufus to 102. "I rather expected to live a long life," says the 89-year-old Long Beach, Calif., resident. "I think it gave me a different view of aging, compared to some friends who had family members die in their 50s and 60s. They're looking for the grim reaper every day."

Harriet Bennish, 56, has lived with no such easy assumption. She feels she dodged an early bullet -- an infected cyst, discovered shortly after her first pregnancy, that required the removal of a kidney. Since that brush with serious illness, the Long Beach singer and actress has made it a point to exercise daily and eat a mostly vegetarian diet to stay as healthy as she can.

Death, its cause and its timing, remains mysterious. Early skirmishes with disease and stark statistics listing leading killers for each decade of life offer clues as to when and how the end will come. So do genes -- parents who died young or relatives who lived to remarkable ages.

But although the specter of genes looms large in the popular imagination, they can be warning posts, not destiny. "The heritability of human life span is actually rather low," says Caleb Finch, professor of gerontology at the University of Southern California.

Even identical twins, once they're in their 70s -- an age that most Americans reach -- are no more likely to die of the same disease than any other two people, he says.

"The genetic influences account for about 30 percent of aging problems," says Dr. Moira Fordyce, geriatrician at Stanford University School of Medicine. "The other 70 percent comes from lifestyle."

The contribution of genes does wax and wane. We face specific risks depending on our age. From early to mid-adulthood, those risks are based largely on chance and genetics. For people who make it to late adulthood, the risks come down to the biological aging process, known as senescence, that all humans experience.

But even from one's 30s to one's 60s, when premature death often is linked to genes through a predisposition to cancer or other disease, the land mines of inheritance often can be avoided.

A family history of early heart attack, for example, is a strong motivator to exercise, control weight and take blood pressure and cholesterol-lowering drugs if necessary, all of which can even the playing field.

A family history of cancer is good reason to take every preventive step possible, including routine screenings.

Early deaths are always tragic, sometimes with no more comforting explanation than the hand of fate. Infants and children die of birth defects, SIDS, pregnancy complications and rare childhood cancers.

By adolescence, the leading causes of death are violent: accidents, suicide and homicide.

By the mid-30s, there's a definite fork in the road leading to two fundamentally different paths. Luck is still a player on each path, in the guise of genetic predisposition to disease or lack thereof. But obesity, poor nutrition habits, smoking, lack of exercise or excessive drinking can send people down a path toward premature death despite good longevity genes.

And good lifestyle habits, cancer screening tests and cholesterol- and blood pressure-lowering drugs -- even in the face of a family history of early death -- can help people navigate the other path, toward ripe old age.

Regardless of how Grandma and Grandpa died, it's a good idea to be realistic. Death comes to all. Without dwelling on morbidity, people can eat right, exercise and do what they can to remain as healthy as possible.

"There are people who don't manage to think about death at all. They might pay a price," says Dr. Robert Butler, president of the International Longevity Center and Pulitzer Prize-winning author of Why Survive: Being Old in America. "You don't want to spend your life morbidly thinking about your old age and death. But you want some sort of balance between that and total blind faith."

A stark reminder often comes when parents die. "That's a call to arms in the reality of life and death," Butler says. "You see yourself as the next in line."

The best shot at a long and healthy life is to live the healthiest lifestyle possible in the time you've got left. Better now than never. "No sense crying over spilt milk," Butler says. "It's never too late to start. Take the stairs. Modify your diet."

Susan Brink writes for the Los Angeles Times.

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