May 10, 2019 | By Jean-Marc Fix, FSA, MAAA | Life/Health
VP, Actuarial Research and Development, Stamford
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
·
Survivors - People who had an age-associated illness but survived.
·
Delayers - People who did not have any disease related to aging until
their 80s (the most common group).
·
Escapers - People who did not get an age-related illness until past
the age of 100. The patterns are quite different by gender, with more women
centenarians (three out of four) and supercentenarians (nine out of 10).
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.
So, is it in the genes?
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?12No
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.”
Endnotes
1. Centenarians are among the
fastest growing population segment: “An Aging Nation: The Older Population
in the United States,” Population Estimates and Projections, Jennifer M.
Ortman, et al., US Census, May 2014, p25-1140.
2. “Typologies of Extreme
Longevity Myths,” Robert D. Young, Bertrand Desjardins, Kirsten
McLaughlin, Michel Poulain, and Thomas Perls. Hindawi Publishing Corporation,
Current Gerontology and Geriatrics Research, Volume 2010, Article
ID 423087.
3. “Emergence of
supercentenarians in low mortality countries,” Jean-Marie Robine (INSERM, Val
d'Aurelle, 34298 Montpellier, France) and James W. Vaupel (Max Planck,
Institute for Demographic Research, Rostock, Germany).
4. Ibid.
5. “Morbidity Profiles of
Centenarians: Survivors, Delayers, and Escapers,” Jessica Evert, Elizabeth
Lawler, Hazel Bogan and Thomas Perls. Journal of Gerontology: Medical Sciences,
2003, Vol. 58A, No. 3, 232-237.
6. “Frailty and Associated
Factors among Centenarians in the 5-COOP Countries,” Marie Herr, Bernard Jeune,
Stefan Fors, Karen Andersen-Ranberg, Joël Ankri, et al. Gerontology, 2018,
64 (6), pp.521-531.
7. “Characteristics and
Incidence of Chronic Illness in Community-Dwelling Predominantly Male U.S.
Veteran Centenarians,” Dept. of Health & Human Services, HHS Public Access,
Author manuscript; available in PMC 2018 September 01; Published in final
edited form as: J Am Geriatr Soc. 2017 September; 65(9): 2100-2106.
doi:10.1111/jgs.14900.
8. “Effect of Exceptional
Parental Longevity and Lifestyle Factors on Prevalence of Cardiovascular
Disease in Offspring,” Dept. of Health & Human Services, HHS Public Access,
Author manuscript; available in PMC 2018 December 15; Published in final
edited form as: Am J Cardiol. 2017 December 15; 120(12): 2170-2175.
doi:10.1016/j.amjcard.2017.08.040.
9. “Do the Offspring of
Centenarians Have Good Health Habits?” J Drury, S Sidlowski,
B Leonard, M Hsu, M Mostowy, S Andersen, and T Perls,
Innovation in Aging, 2018 Nov; 2(Suppl 1): 31. Published online 2018
Nov 11.
10. “The genetics of extreme
longevity: lessons from the New England Centenarian study,” Paola Sebastiani
and Thomas T. Perls, Frontiers in Genetics, Review Article published:
30 November 2012.
11. “Resilience as a Factor of
Longevity and Gender Differences in Its Effects,” Martin Lakomý and Marcela
Petrová Kafková, Czech Sociological Review, 2017, Vol. 53, No. 3.
12. The Targeting Aging with
Metformin Trial, American Federation for Aging Research, https://www.afar.org/research/TAME.
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