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Centenarians Lead the Way to Longer Lives
A study is looking at centenarians, whose population is increasing, to see what they have in common. Genetics plays a part, as does staying lean and not smoking.Click here to view article.
John’s retirement community has a party each year for residents who are 90 and over, and each year the party gets larger (although probably not more boisterous). John himself, at age 91, is in good health, with no major problems except for loss of short-term memory. Even in his early 90s, he doesn’t need glasses.
John is one of a growing number of Americans who are living past 85, and an increasing number into their 100s. The U.S. Census Bureau reports that those age 85 and over “are the most rapidly growing elderly age group. Between 1960 and 1994, their numbers rose 274 percent. In contrast, the elderly population in general rose 100 percent and the entire U.S. population grew only 45 percent.” The Census Bureau projects that the 85 and over population could grow from 5.5 million in 2010 to 19 million by 2050.
To find out what keeps certain men and women living and staying healthy longer, the New England Centenarian Study from the Boston University School of Medicine is studying people age 100 and over.
When the centenarian study began in 1994, the number of centenarians (those 100 and over) in industrialized countries, including the United States, was 1 per 10,000. Today, the figure is about 1 per 6,000, making centenarians one of, if not the fastest growing segments of the population. Although started in Boston, the study has expanded to include centenarians from throughout the United States and other countries and has become the largest comprehensive study of centenarians around the globe. Not only does the study include 1,600 centenarians but is also the biggest sample (approximately 107 people) in the world of supercentenarians (age 110-plus). As of 2010, there were about 80,000 centenarians in the United States, mostly women (85 percent).
Because centenarians don’t become disabled until the end of their lives, the New England study views them as good models of aging well. Looking at its subjects’ ability to avoid diseases later in life, the study concluded that “we believe that instead of the aging myth ‘the older you get, the sicker you get,’ it is much more the case of ‘the older you get, the healthier you’ve been.’”
When the study looked at geography—that is, claims that people in certain regions live longer—it could find no evidence. Yet it recommends more study of people in certain areas who live longer and have more active lives, such as men between the ages of 80 and 99 in the Tibetan mountains who still herd livestock and lead physically strenuous lives.
Characteristics of Centenarians
Although the New England study found that centenarians varied widely in years of education (zero years to post-graduate), socioeconomic status (very poor to very rich), religion, ethnicity and patterns of diet (strictly vegetarian to extremely rich in saturated fats), they found a number of characteristics in common:
- Few centenarians are obese. In the case of men, they are nearly always lean.
- Substantial smoking history is rare.
- Centenarians may be better able to handle stress than the majority of people.
- Not all centenarians show signs of dementia, and some had healthy-appearing brains.
- A woman who naturally has a child after the age of 40 has a four times greater chance of living to 100 compared to women who do not. A late pregnancy may be an indicator that the woman’s reproductive system is aging slowly and that the rest of her body is as well.
- At least 50 percent of centenarians have first-degree relatives and/or grandparents who also achieve extremely old age, and many have exceptionally old siblings. Male siblings of centenarians have a 17 times greater chance than other men born around the same time of reaching age 100, and female siblings have an 8.5 times greater chance than other females born around the same time of achieving age 100.
- Many of the children of centenarians (age range of 65 to 82) appear to be following in their parents’ footsteps with marked delays in cardiovascular disease, diabetes and overall mortality.
- Some families demonstrate exceptional longevity that cannot be due to chance and must be due to familial factors.
- The offspring of centenarians, compared to population norms, score low in neuroticism and high in extraversion.
The Role of Genes Versus Environment
Scientists have long debated the role of nature versus nurture: Studies of identical twins reared apart, for example, have shown 70–80 percent environmental influence and 20-30 percent genes. However, the New England Centenarian Study discovered that exceptional longevity (living over the age of 100) runs strongly in families. Other study results strongly suggest that the genetic component of exceptional longevity gets larger and larger with increasing age and is especially high for those age 106 years and older. The New England study was particularly interested in how centenarians are able to markedly delay, or in some cases escape, Alzheimer’s disease.
Researchers performed detailed and annual neuropsychological examinations on centenarians in the Boston area. The study concluded that most people have the genetic makeup to live into their mid- to late 80s in good health, and like centenarians, compress the time they are sick toward the end of their lives. Much of their ability to do so depends upon healthy behaviors, including not smoking, strength-training exercise and a diet conducive to being lean. Other studies have found that a sense of humor, playing music and a strong social system contribute to living over 100.
Recent Scientific Breakthroughs
Science is making discoveries that could keep people living even longer than 100-plus. In March, Sciencemagazine announced that a team led by an Australian researcher found that targeting a single anti-aging enzyme in the body has the potential to prevent age-related diseases and extend lifespan. This means that a whole new class of anti-aging drugs could ultimately prevent cancer, Alzheimer’s disease and Type 2 diabetes.
“The target enzyme, SIRT1, is switched on naturally by calorie restriction and exercise, but it can also be enhanced through activators. The most common naturally-occurring activator is resveratrol, which is found in small quantities in red wine, but synthetic activators with much stronger activity are already being developed.”
In May, a team of 70 scientists from the United States, China, Australia and Japan reported that it sequenced and annotated the genome of the lotus plant, which is believed to have a genetic system that repairs genetic defects and may hold secrets about aging successfully (“Research may help scientists learn anti-aging secrets of sacred lotus,” Medical.net).
“The lotus genome is an ancient one, and we now know its ABCs,” says Jane Shen-Miller, one of the researchers and a senior scientist with UCLA’s Center for the Study of Evolution and the Origin of Life. “Molecular biologists can now more easily study how its genes are turned on and off during times of stress and why this plant’s seeds can live for 1,300 years. This is a step toward learning what anti-aging secrets the sacred lotus plant may offer.”
Longevity research seems to be increasingly aimed not at getting people to live longer but, if they are going to live longer, to stay healthy. In the New England study, nonagenarians (subjects in their 90s), centenarians (ages 100–104), semi-supercentenarians (ages 105–109) and supercentenarians (ages 110+) had progressively shorter periods of their lives spent with age-related diseases. These findings support the hypothesis, known as the compression of morbidity, that as one approaches the limits of lifespan, diseases (morbidity) must be delayed (or escaped) toward the end of these longest lived, and that there truly is a limit to human life span and that this limit is around 110–125 years.
Despite this finding, the field of increasing our lifespan, known as life extension science, is a large one and appears to be growing (see sidebar).
Ideas for Extending Life
Many theories and ideas for living a longer life are either unproved, experimental or have worked in limited situations:
- Preliminary studies of caloric restriction on humans have provided some evidence that caloric restriction may have powerful protective effects against secondary aging in humans, such as Type 2 diabetes and atherosclerosis.
- The free-radical theory of aging, which states that organisms age because cells accumulate free radical damage over time, suggests that antioxidant supplements, such as vitamin C, vitamin E, Q10, lipoic acid, carnosine and N-acetylcysteine, might extend human life. Other trials suggest that beta-carotene supplements and high doses of vitamin E increase mortality rates.
- Resveratrol, a protein stimulant, appears to extend lifespan in simple organisms such as nematodes and short-lived fish.
- Some supplements, including the minerals selenium and zinc, have been reported to extend the lifespan of rats and mice, though this is not proven in humans.
- Future advances in nanomedicine (the manipulation of matter on an atomic and molecular scale) could give rise to life extension through the repair of many processes thought to be responsible for aging, such as damaged cells.
- Therapeutic cloning and stem cell research could one day provide a way to generate cells, body parts or even entire bodies (generally referred to as reproductive cloning) that would be genetically identical to a prospective patient.
- In gene therapy, artificial genes are integrated with an organism to replace mutated or otherwise deficient genes.
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