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Centenarians are rare, but they are among the fastest growing population segments in the U.S. and throughout the developed world - and what is rare is special. But why are they special? Unfortunately, we humans are better at rationalizing than at rational thought, as the prevalence of superstition throughout history clearly demonstrates.1
As a matter of fact, when researchers looked at evaluation of claims of extreme old age, they encounter a number of archetypes.2 Some of the most interesting and still pervasive myths are: the fountain of youth myth (a special substance will make you live longer); the Shangri-La myth (living in a special place will make you live longer); the village elder myth (where old, generally men, live longer and that’s why our village is the wisest); the spiritual practice myth (special spiritual rituals and practices will make you live longer); and, finally, still quite active today, the national longevity myth (in our country, people live longer because we are superior). Not all myths are necessarily false. There are some areas with a higher density of verified centenarians than others, for example, the famed Blue Zones.
Many in the scientific community believe that there are lessons to be learned, and I agree. As mortality has improved and the number of centenarians has increased, determining the “special element” becomes more difficult as some people are just lucky.
Research has now turned to study supercentenarians who have reached the age of 110 - truly rare in the world with only a few hundred of them identified.3 In fact, documented supercentenarians are a recent phenomenon with one or two emerging in the 1960s and the population exploding, relatively speaking, since the late 1970s.4
We have known for some time that centenarians fall into three groups:5
Frailty is an important criterion to understanding mortality in the elderly and is commonly reviewed as part of our elderly underwriting. In a recent study by Herr et al., of over 1,000 centenarians in five countries, frailty was defined by weight loss, fatigue, weakness, slow walking speed, and a low level of physical activity. She found that more than 65% of the centenarians had at least three criteria, and over one-third had four or five.6
Paradoxically, research from Kheirbek on male U.S. veterans comparing octogenarians, nonagenarians and over 3,000 centenarians, found that centenarians had less incidence of chronic illnesses than octogenarians. For instance, the rate of hypertension was over 29% in octogenarians but 3% in centenarians.7
A recent article by Gubbi shows that offspring of parents with exceptional longevity, themselves known to live longer, have the same prevalence of obesity, smoking, alcohol use and physical activity as the offspring of parents with usual mortality. On the other hand, they are approximately one-third less likely to have hypertension or cardiovascular disease and two-thirds less likely to have had a stroke.8
Another recent article on the offspring of centenarians by Drury contradicts the numbers for obesity and smoking and adds more dentist visits as a factor because oral hygiene is a risk factor for cardiovascular disease.9 The jury is still out on the risk profile, but what emerges is that centenarians and their offspring are less affected by specific risk factors than the rest of us.
There is a strong body of evidence for familial longevity that suggests a genetic component. Sebastiani found that centenarians have as many disease-associated gene variants than the general population. What seems to make supercentenarians genetically special may be a higher prevalence of genes countering the effects of the deleterious mutation.10 Genetic analysis of that population shows that there are no magic genes, but a series of genes helping to cope with dangerous risk factors.
This resilience gives rise to the hope that geroscience, which focuses on combatting aging instead of specific diseases, may hold promise for all of us. It is interesting to note that resilience may not just be physical but also mental. A study by Lakomy points to psychological resilience as a predictor of longevity, with an especially significant impact on women, which could explain the gender inequality that we see at the oldest ages.11
We are also learning about the epigenetic (external impact on gene expression), proteomic (how genes are activated and expressed), and microbiome (impact of microbial life in our gut) components of longevity.
Will the drug metformin, typically used in the treatment of diabetes, be the fountain of youth?12 No one knows yet, but I am optimistic that by understanding the complexity of the different layers that contribute to longevity, we are closer to achieving meaningful results in extending life span - and more importantly for society and for us personally, an extension that is healthy.
This blog originally appeared in our e-newsletter series “The Future of Old Age - Insights for Insurers.”
