The following article comes from the U.S. News ebook, How to Live to 100, which is now available for purchase.
The raw number of centenarians in America is increasing. Fast. In fact, they are one of the fastest-growing demographic groups in the country. Currently, there are about 70,000 Americans who have reached the elusive 100 mark, but that number is expected to rise to about 600,000 by 2050, according to the U.S. Census Bureau.
What is it that keeps their bodies humming along decades longer than average? In recent years, results from studies of centenarians have begun to offer answers, and it looks increasingly like there's no simple cause that confers extreme longevity—be it genetics, lifestyle, or personality—and no (at least at this point) quick fix or pill that's guaranteed to get you to 100.
[See: World's Oldest People]
But the research has revealed some telling clues about what it takes to reach three digits. First, women have a distinct advantage. About 85 percent of centenarians are women, and among an even more select group of supercentenarians (people 110 or older) the number jumps to about 90 percent. The men who do survive to 100, however, tend to be healthier and more fit than their female counterparts, perhaps because women are better at managing age-related illnesses like cardiovascular disease and cancer.
Not surprisingly, few centenarians are obese and few smoke or drink. Most seem skilled at handling stress and find ways to process problems quickly, brushing them away rather than dwelling on them. A study of centenarians from the state of Georgia found they were more emotionally stable, extroverted, conscientious, and active in the community than their shorter-lived peers.
When a person is born even seems to make a difference. A study of 1,574 American centenarians and more than 10,000 of their shorter-lived siblings and spouses led by Leonid Gavrilov and Natalia Gavrilova of the University of Chicago found that babies with a fall birthday have a slightly higher chance of becoming centenarians than babies born in spring months.
The Gavrilovs haven't pinpointed why yet, but they suspect that environmental conditions early in life are responsible for the difference. Women don't eat as well during the winter, for example, and have less exposure to light and vitamin D, both factors that could have lasting negative impacts on developing spring babies.
Few things seem to be as important as having a long-lived family, says Thomas Perls, associate professor of medicine at Boston University. Perls, who manages a study of nearly 1,600 centenarians, the largest in the world, has shown that about 50 percent of centenarians have first-degree relatives or grandparents who also achieve very old age, and many have exceptionally old siblings as well. Men with centenarian siblings have nearly a 17 times greater chance than other men of living to 100; women with centenarian siblings have a 9 times greater chance.
Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine, agrees. He's studying a population of 500 generally healthy, vital Ashkenazi Jews between the ages of 95 and 112. His goal is to identify longevity genes—then create drugs that bestow that protection on those with fewer inherited gifts. "The fact is we have plenty of overweight centenarians, plenty who smoke, plenty who drink," says Barzilai. "With the right genes, the body can put up with all sorts of abuse."
Researchers have found that a number of gene combinations—not just one or two—have a bearing on longevity. Barzilai's group has shown, for example, that centenarians tend to have a variant of a particular gene called CETP that protects against cardiovascular disease and dementia by boosting levels of HDL, or "good" cholesterol. Already, the pharmaceutical giant Merck is testing a drug that mimics the protective CETP variant on people with heart disease.
Genetic analysis of centenarians demonstrates that multiple genes—including variants of the FOX3 and APOE genes—may also confer protective benefits. Barzilai and other longevity researchers expect that genetic clues from centenarians will lead to numerous drugs that shield against age-related diseases in the future.