The centenarians in the study indulged in smoking and drinking just as much as their shorter-lived counterparts. They did not appear to follow healthier or more stringent diets than others in the general population. They were also just as likely to be overweight, and may even have exercised less. So what contributed to their unusually long lives?
Scientists have long debated the roles of nature and nurture in longevity. Centenarians are, for example, far more likely than the average person to have long-lived relatives, suggesting that long life may be largely inherited. And yet studies have shown that identical twins separated at birth and reared apart can have vastly different life spans — with one living exceptionally long, and the other dying long before — indicating that genes have only so much influence.
The new findings, part of an ongoing look into longevity by researchers at the Albert Einstein College of Medicine, focused on Ashkenazi Jews, a group that is more genetically homogenous than other populations, making it easier to identify genetic differences that contribute to life span. In the study, the researchers followed 477 Ashkenazi centenarians who were 95 or older and living independently. They asked them about their habits and the ways they lived when they were younger. Using data collected in the 1970s, the researchers compared the long-lived group with another group of 3,000 people in the general population who were born around the same time but who generally did not make it to age 95.
They found that the people who lived to 95 and beyond did not seem to exhibit healthier lifestyles than those who died younger. Forty-three percent of the male centenarians reported exercising regularly at moderate intensity, compared with 57 percent of men in the other group. About 24 percent of the men in the older group drank alcohol daily, compared with 22 percent in the other group. Among women, they found that the same percentage in both groups reported following low-calorie diets.
Almost 30 percent of the women who lived exceptionally long were smokers, slightly more than the 26 percent of women in the comparison population who smoked. About 60 percent of the older men smoked, and 74 percent of their shorter-lived counterparts did.
Men and women in both groups were also just as likely to be overweight as people in the general population. The one difference in that area was that centenarians were less likely to be obese. Only 4.5 percent of men in the older group were obese, compared with 12 percent of the other male subjects. A similar pattern was found among women.
So did all that hard living just make them happier, contributing to their extended life spans? Much has been made over the years about optimism and other social factors that may contribute to longevity. But in the latest study, only 19 percent of the people who lived past 95 said they believed a “positive attitude” played a role in their longevity, while just 6 percent credited their religious faith or spirituality.
Dr. Nir Barzilai, the lead author of the study and the director of the Institute for Aging Research at Einstein, said that many of the centenarians he has studied over the years do in fact seem to have optimistic or positive outlooks on life. But it’s unclear if a lifetime of positive thinking got them to a healthy old age, or if they developed a positive outlook much later in life as they realized their good fortune.
“It’s very hard for us to answer these questions,” he said. “Is it possible that everyone who was born in 1910 and went through the Depression and many wars is looking at life now and saying, ‘It’s pretty good, I should be happy’?”
Dr. Barzilai said he had interviewed many adult children of centenarians who swear that their parents changed in many ways between 80 and 100.
“The children will say, ‘Yeah, they’re agreeable now, but you should have seen them when they were 60 or 70, they were so obnoxious,’” he said.
One finding that was not surprising in the latest study: About a third of the people 95 or older reported having many long-lived family members. Previous studies of Ashkenazi Jews have helped pinpoint a gene variant in this population that causes significantly elevated levels of HDL, or “good” cholesterol, in centenarians that appears to confer resistance to heart disease and Alzheimer’s. For people who don’t have the gene variant, there is potential good news, Dr. Barzilai said: One drug company is currently developing a drug that has the same effect on HDL.
Other studies have shown very slightly decreased levels of thyroid function in people who live longer, as well as in their siblings and offspring, which has opened the door to another line of genetic research.
“We’re identifying genes that play a role in aging,” Dr. Barzilai said, “and then we can design drugs to mimic their actions.”
Dr. Barzilai said it is clear from research on centenarians that reaching 100 years of age is not just a matter of adopting healthy habits; having the right genes appears to greatly improve the odds. But he is nonetheless very much a supporter of the mantra that diet and exercise are crucial, especially for those without a string of long-lived parents, aunts and uncles.
“If you listen to what your doctor is telling you and you watch your weight, drink a glass of wine a day, exercise, avoid smoking and treat any conditions like high blood pressure,” he said, “you’re still likely to get to be over the age of 80.”