Last summer, scientists reported on another possible calorie-restriction mimetic. Three teams found that feeding older mice a drug called rapamycin, an immunosuppressant used to prevent organ rejection in transplant patients, significantly extended their lives, apparently by inhibiting an enzyme that is linked to the aging process. It was comparable to adding a robust decade to a human life span, says David Harrison, a professor at the Jackson Laboratory in Bar Harbor, Maine, who led an arm of the study. That doesn't mean people "should start popping rapamycin," says Harrison; among the possible side effects is susceptibility to infection. But if several large demographic studies eventually show that longtime rapamycin users seem to be fending off a wide range of age-related diseases and an effective dose is found, says Harrison, "I'm going to start taking it."
Don't expect to see an age-slowing drug approved anytime soon, researchers say. The Food and Drug Administration does not consider aging a disease; without an illness to treat, there can be no drug to approve. But the research may yield a crop of drugs that could be OK'd for specific conditions, such as diabetes, and then are later found to protect against others. "If we're slowing aging, then we should be slowing the onset and progression of most, if not all, age-associated disease processes," says Kaeberlein. A picture may gradually emerge, says Steven Austad, a biogerontology professor at the University of Texas Health Science Center in San Antonio, that "hey, this thing seems to keep people from getting cataracts. And wait a second, all those people don't seem to be getting cancer, either."
Clues from the very old
Living to 100 didn't get the warm reception Thomas Perls had expected when his book came out in 1999. He thinks the public assumed that anyone that old "must be in terrible shape." But Perls, who directs the New England Centenarian Study, has found that the vast majority of the centenarians in his sample are doing surprisingly well. Most are free of disabilities until the end of their lives—even those contending with significant age-related ailments, like heart disease. And the 1 out of 7 million people who reach the "supercentenarian" age of 110 and beyond (there are 85 in his study) seem to dodge not only the effects of age-related conditions but the illnesses themselves. Or if they do become ill at the end of their lengthy lives, they quickly die rather than languishing in declining health.
What's the secret of the oldest old? "Our hypothesis is that centenarians get to be 100 because they have some protection against age-related disease and maybe against aging," says Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine in New York, who has studied Ashkenazi Jewish centenarians and their children for a decade. "When you ask them why they live to be so old, you get this fascinating story. … They've done nothing right. Some have been smoking for 95 years. There's no one who exercises regularly."
Both Barzilai and Perls are hunting for hints to healthy longevity in those who hit 100 to learn what it is about their genetic makeup that seems to help them along and whether that could help those of us with fewer genetic gifts. Nearly a quarter of Barzilai's 500 centenarians, for example, have a mutation that bestows on them levels of "good cholesterol" as high as triple normal concentration. He has found that those with the mutation also are largely immune from Alzheimer's disease and apparently have lower risk of heart disease, high blood pressure, and diabetes.
Even without miracle drugs, those of us who didn't "win the genetic lottery at birth," as Olshansky puts it, could add many years to our lives. "We are living about 10 years less than our potential … mostly due to bad health behaviors," says Perls. Evidence comes from groups of similar individuals who do the right thing. Seventh-Day Adventists, for example, have an average life expectancy of about 88 years, the highest in the United States, he says. (The U.S. average is 78.) Adventists avoid red meat (many are vegetarian), exercise regularly, and don't drink alcohol or smoke. Their focus on religion and family may ease stress, itself a risk factor. "That's kind of the recipe," says Perls. It's one that doesn't rely on research breakthroughs, either. But even if a means to slow human aging and extend healthy human life spans eventually emerges from the laboratory, says Austad, "You could still get hit by a car or your parachute doesn't open when you're sky diving." Science can't eliminate chance or bad luck.