Through a combination of genetics and lifestyle, some individuals are able to either avoid or survive the age-associated medical problems that end most lives. In fact, many nonagenarians and centenarians are often healthier and more active than their slightly younger counterparts and have mortality rates after the age of 97 that are actually lower than expected. According to a hypothesis by gerontologist James Fries, disease and disability tend to be compressed into a much later and shorter period of time for those living toward the frontier of the age span, up to and beyond 100.
Studies of centenarians have yet to identify any genes that bring longevity, but they have elucidated several common lifestyle characteristics. Centenarians, on average, have delayed onset of most diseases, especially the main killers — heart disease, stroke and cancer. They are rarely obese, tend not to smoke or drink alcohol to excess, and often have similarly old siblings (There are, of course, outliers like Frenchwoman Madame Jeane Calment, the oldest recorded living human being, who died in 1997 at the age of 122. She reportedly smoked and drank a glass of port twice a day up until the age of 117!). And centenarian women often had their children after the age of 35 or 40, perhaps an indication of the hardiness of their reproductive systems.
We also see that these older minds, when intact, share several common features. Compared to their younger peers, centenarians cope better with stress, tend to be more confident and independent, are generally less anxious and depressed, and have increased levels of life satisfaction, even when their functional limitations are greater. In addition, research with centenarians has found much lower than expected rates of dementia — roughly in the range of 15 to 30 percent. There may be several reasons for this, including more connections between neurons and less genetic susceptibility to Alzheimer's disease. Whatever the factors may be, they cast a ray of light along the frontier.
Despite these findings, clinicians often assign mythic status to their oldest patients and try not to intervene too much when problems arise. I remember being asked to treat a 106-year-old woman who was wheeling up and down the hallway of the nursing home and banging her cane on other residents' doors. My initial treatment plan of "do nothing and let the woman alone" lasted about one week until staff demanded that I intervene more effectively. I was squeamish, worried that my pharmacologic hand might wield the harpoon that dealt the final blow to this majestic life. I pretended she was a mere 90 years old and started her on a low-dose antipsychotic, to good effect. Her 84-year-old son appeared the next week to thank me. "She's happier, and so am I!" he exclaimed. The frontiers of aging had truly fallen, I concluded.
From How We Age: A Doctor's Journey Into the Heart of Growing Old by Marc Agronin, M.D. Reprinted courtesy Da Capo Lifelong Books. Read an interview with Marc Agronin.