Healthy Aging and Longevity
What Our Healthy Elders Teach Us: Blue Zones, Centenarians, and Elderly Twins
This is one of three articles on healthy aging and longevity. Companion articles include:
Much of what scientists have learned about the oldest-old comes from observational research on three types of healthy agers: Blue Zone elders, centenarians, and elderly twins.
Here are a couple of widely accepted conclusions investigators have reached after decades of observational research on studying the oldest-old, from inner-city New York to the mountains of inner Sardinia.
- Even in old age, they are quite healthy. Though they are universally frail and often disabled, they escape common age-related diseases, such as cancer and cardiovascular disease.
- They share certain attitudes which might confer advantages. As measured by standardized tests, the two most common psychological traits shared by extremely old people are resilience and level-headedness. As a result, despite their infirmities, their life satisfaction remains high.
- They enjoy powerful social support networks. Most long-lived individuals are sustained by deep connections with friends and family.
- Some of them benefit from lucky genes. A decent proportion of exceptional agers are blessed with longevity genes, and on average, this proportion increases with age.
Let’s look at the evidence.
Blue Zone Elders
In 2004, Michael Poulain and Giovanni Pes, along with other longevity scientists, led a study looking at extreme longevity on the Italian island of Sardinia, which boasts an unusually high proportion of long-lived individuals. These researchers coined the term “Blue Zones” to describe these geographic areas. Since then, scientists have studied healthy agers from other, similar locales, including Okinawa (Japan), Loma Linda (USA California), Nicoya Peninsula (Costa Rica), and Ikaria (Greece). These Blue Zones were popularized by Dan Buettner in a 2005 National Geographic magazine cover story and subsequent book.
Blue Zones tend to be in isolated communities where a healthy lifestyle, diet, social context, and outlook are culturally determined and built into the social order. Prominent gerontologist Leonard Poon explains that,
“Blue Zone populations are geographically and/or historically isolated (islands and mountainous regions). These populations succeeded in maintaining a traditional lifestyle implying an intense physical activity that extends beyond the age of 80, a reduced level of stress, and intensive family and community support for their oldest-olds as well as the consumption of locally produced food.”
Geriatrician Robert Pignolo summarized common themes from the large body of observational research on Blue Zone lifestyles which may affect longevity, and I’ve sprinkled in other findings. These include:
- Diet and nutrition. Eating locally sourced, plant-rich meals, which include red meat and fish a couple of times each week. Eating in moderation with small- or moderate-portioned meals and a lighter meal at the end of the day. Consuming beverages such as goat’s milk, red wine, and herbal teas.
- Body weight. Maintaining a healthy body weight with minimal abdominal fat and avoiding obesity.
- Attitude and resilience. Living with purpose through a positive life philosophy, volunteerism, and hard work. Responding to challenges without feeling anxious or victimized.
- Social resources. Enjoying extensive interactions with family and friends, having fun, and laughing a lot.
- Physical activity. Engaging in daily physical activity, especially walking and gardening.
- Spirituality. Participating in organized religions, some of which call for periodic day-long fasts.
- Other possible factors. Sunshine, lack of extreme weather or temperature, adequate hydration, naps.
While the life circumstances observed in Blue Zones are difficult to emulate in modern urban settings, the public has embraced the allure of Blue Zone precepts around diet, attitude, and lifestyle.
Picturing the Blue Zone lifestyle provokes a certain comforting nostalgia that practically compels one to consider ways to copy it. However, there’s something that complicates this otherwise perfect picture of healthy aging. Observational research like this can only show correlation and cannot prove causation. Accordingly, some scientists believe that Blue Zones are longevity hotspots simply because they are physically and culturally isolated — not because their inhabitants are any more or less healthy than those in nearby towns and regions.
When looking at Blue Zones, here’s something to keep in mind. Isolated populations such as these often have a stable gene pool with limited influx from genetically different people, so there’s potential for clustering of genes which impart longevity advantages to those who survive demographic and selective forces, such as centenarians. We get into longevity genes in my companion article, but one reason Blue Zone inhabitants live to a healthy old age is that they probably inherit some.
For instance, when researchers examined the siblings of Okinawan centenarians that did not live to become centenarians themselves, the found that these relatives lived a whopping twelve years longer than other Okinawans who were born the same year they were. This points to a strong genetic component involving Okinawan super-agers and their families. To put an even sharper point on it, based on deep genetic profiling of the Okinawan population, investigators concluded that,
“Okinawans have varied little ethnically, historically having married within their own villages, and there is little evidence of substantial gene flow for centuries, resulting in what appears to be less genetic variability in Okinawans than in other Japanese.”
Because of this (as well as the small study populations) Blue Zone observational research shouldn’t be taken as the final word on healthy aging. To be sure, Blue Zone populations probably benefit from both genetic and lifestyle advantages. In order to better understand and isolate lifestyle factors, it’s important to study a more randomized cohort of the oldest-old. Which is exactly what researchers that study centenarians and elderly twins seek to do.
Centenarians
A hundred years ago, the average woman lived to 58 years of age, and the average man to 53. Which means that an individual over one hundred years old that’s alive today has survived almost twice as long as the average for the cohort they were born into. To unravel the mystery behind their exceptionally extended healthy lifespans, scientists have been studying centenarians for decades.
In 1975, researchers established the first centenarian study of people living on the Japanese island of Okinawa. The Okinawa Centenarian Study is now the longest continuously running such study, having examined more than 1,000 Okinawan centenarians thus far. While this cohort is not randomly drawn from genetically diverse populations, the Okinawan lifestyle just might teach us something about healthy aging. Scientists are drawn to Okinawa not only because this island prefecture has a much higher proportion of long-lived individuals, but also because the traditional Okinawan diet is distinctively different from the Mediterranean diet (it is lower in fat and higher in phytonutrients), and because Okinawan centenarians have remarkably low rates of cardiovascular disease.
Compared to Blue Zones work, centenarian studies enjoy greater scientific weight, because they manage to enroll large numbers of (often) randomly-selected subjects who — unlike Blue Zone cohorts — often come from a wide range of locations and life circumstances. Below are some of the most important study cohorts.
- The New England Centenarian Study now includes about 1,600 centenarians from all over the U.S. and 500 of their children (who are in their 70s and 80s themselves). Other U.S. study cohorts include the Ashkenazi Jewish Centenarian Study and the Georgia Centenarian Study.
- European and Asian study cohorts now include Italian, Sardinian, Danish, Swedish, Tokyo, Okinawan, Korean, and Chinese individuals.
- Study groups of healthy agers not specifically focused on centenarians include the Seven Countries Study (which began back in 1958), and the gigantic Chinese Longitudinal Healthy Longevity Survey, which includes data on more than 16,000 centenarians and 100,000 elders in total.
All these long-running efforts have contributed enormously to our understanding of lifestyles and behaviors that are associated with healthy aging, spawning thousands of articles, hundreds of newly minted PhDs, and scores of books.
First, the bad news. It turns out that, while centenarians are lauded for their extraordinary resilience, on average it still feels especially uncomfortable to live much beyond one hundred years old. People surviving this long generally delay the onset of disability until well into their nineties, but not much beyond that. In one study, the vast majority of centenarians were judged to be “severely impaired” in their physical capabilities. Moreover, the prevalence of dementia rises sharply after ninety years of age. One study found that just one in five centenarians manages to escape any chronic problems, while a different study pegged it at far less than this. Yet another research effort showed that only ten percent of centenarians avoid needing any assistance with the activities of daily living. Bottom line? Vital, independent centenarians are few and far between.
But frailty is not the same thing as having a mortal disease — something that extremely old people manage to escape. In fact, those exceedingly rare individuals who live beyond 110 years of age arrive at this milestone in pretty decent health. In 2012, researchers evaluated the health of over 1,500 centenarians, and placed them in one of three self-explanatory categories — “survivors,” “delayers,” and “escapers.” While a robust one-third of “young” centenarians aged 100 to 104 escaped any of the most prevalent and deadly age-related diseases, this climbed to an impressive two-thirds of subjects over 110 years old (who were certainly frail, but not disease-ridden). For these incredible supercentenarians, investigators explain that “healthspan approximates lifespan.”
Elderly Twins
As with centenarians, scientists have also created study cohorts of elderly twins. Some of the most influential include the Danish Twin Register (established in the 1950s) and the Swedish Twin Registry (the largest in the world at more than 85,000 twin pairs). For obvious reasons, work on identical twins is particularly helpful in evaluating the way that genes influence longevity and healthy aging. For example, it is through twin studies that investigators were able to show that genetic factors explain much of the variability in metabolic health, a major factor associated with extended healthspan and lifespan.
If you wish to dig deeper into the genetics of healthy agers, check out my companion article here.
Takeaways
In this article, we saw that studying various cohorts of healthy elders offers tantalizing clues about why and how they manage to escape age-related diseases. Here are the takeaways from each of these cohorts.
Blue Zones. Isolated Blue Zone elders share some common characteristics, perhaps because they live traditional lifestyles in isolated areas. These include eating locally-sourced foods in moderation, maintaining healthy body weight, living with purpose and a positive attitude, extensive social connections, and daily physical activity.
Centenarians. While they are often frail, centenarians are surprisingly healthy and contented, and manage to delay and even escape the onset of common age-related diseases.
Elderly twins. Elderly twin studies are especially helpful in understanding the genetic heritability of longevity traits, such as metabolic health.
To learn more, click over to my companion articles, Deep Dive on Longevity Lifestyles and Longevity Genes and Phenotypes.
