Is a person "old" at age 67? Yes, according to a survey of American adults earlier this year made by AARP, the nation's largest advocacy group for older persons.
But what if the typical senior still had 30 years of good physical and mental health left at that age?
For a small but growing number of people, that question is more than hypothetical. The number of centenarians -- people who are 100 years or older -- in the United States has grown 60% since 1990, to about 61,000 people, and will continue to increase in coming decades, according to the Census Bureau. In another 10 years, the number will more than double to over 130,000 people, and it's expected to double yet again to 274,000 in 2025.
Illness Not Always Typical
"Research on centenarians is challenging myths about aging, such as that the older you get, the sicker you have to be," says Thomas Perls, MD, a geriatrician and director of the New England Centenarian Study at Harvard Medical School and Beth Israel Deaconess Medical Center.
Perls and others who are studying the lives of centenarians have found that many have avoided the common chronic illnesses and diseases associated with old age, such as cancer, heart disease, stroke, and Alzheimer's disease.
"Many were relatively healthy well into their 90s. About 15 percent live independently, and about 30 percent are cognitively intact, with the rest displaying a range of mild to severe cognitive impairments," says Perls.
Although centenarians are extraordinary examples of how one can live a long, healthylife, says Perls, "we believe that the vast number of people have genes that will allow them to live to at least 85 years old. People who take appropriate preventive steps may enjoy as many as 10 additional quality years."
The New England Centenarian Study -- which includes more than 200 people in and around the Boston area -- is the subject of a recent book by Perls and two colleagues, "Living to 100: Lessons in Living to Your Maximum Potential at Any Age."
Better Health Habits
Besides their ability to resist disease -- perhaps due to good genes -- centenarians tend to have good health habits. Leonard W. Poon, PhD, director of the Georgia Centenarian Study at the University of Georgia in Athens, says his center's studies show centenarians remained active throughout their lives and smoked, drank, and ate less than other people.
"The nature versus nurture question will be debated for a long time," says Poon, a professor of psychology and director of the university's gerontology center in Athens, Ga. "Yes, there are many centenarians who come from long-lived families; however, there are many centenarians who do not. I believe the answer is that genetics could be important for some but not for others."
The ability to cope with the stress of daily life might also contribute to a longer, healthier life, says Margery Hutter Silver, EdD, a geriatric neuropsychologist and part of the New England Centenarian Study. Centenarians, she says, "were better at handling stress and managing their emotions. They didn't dwell on things that caused stress in their lives."
The centenarians in her study also appeared to stay intellectually engaged in life as they aged. That might mean anything from simply doing the crossword puzzle to writing articles for academic journals, she says.
Lynn Peters Adler, a lawyer and director of the National Centenarian Awareness Project in Phoenix, has interviewed hundreds of centenarians and their families. She's learned, she says, that centenarians have "a remarkable ability to renegotiate life at every turn, to accept the changes and losses that come with age, and not let it stop them. Centenarians are not quitters!"
Perls is skeptical of "quick fixes" promising an easy route to longevity, such as the untested but much-touted "anti-aging" formulas popular now. He and others say that exercising, strength training, eating a healthy diet, avoiding smoking and excessive drinking, learning to manage stress, using your brain, and maintaining links with people are all things people can do to improve their chances of a longer life.
"Many people think life stops after 60," says Perls. "I'd maintain that if you do things right, you could be adding 20 or 25 years of life when you have a good chance of being in good health."