Living Past 100: The Secrets Behind Japan's Growing Number of Centenarians

Established in April 2014 as a center for transdisciplinary geriatric research, the Center for Supercentenarian Medical Research at the Keio University School of Medicine is a world leader in centenarian research, leveraging over twenty years of centenarian data amassed by the Keio School of Medicine in internal studies and joint research with research institutions both in Japan and abroad.

In this exclusive interview, Guest professor Nobuyoshi Hirose gives us a glimpse inside the past two decades of his research, which has helped pave the way for the center’s establishment. Prof. Arai then reflects on what he has learned through his research into mental health among the elderly.

-Prof. Hirose, how did you first get involved in centenarian research?

Hirose: As a geriatric medicine specialist at Keio University Hospital, I treated many elderly patients and found myself wanting to learn more from a general medicine perspective. So, without any experience or initial funding, I began my centenarian research in 1992, but it proved to be quite a struggle.

A turning point in my research came in 1997 when I traveled to Australia for an international geriatrics conference and was first exposed to the centenarian research happening abroad. There I met a research group from the University of Georgia, who offered to collaborate on centenarian research plans, a two-year process that would become the basis for my current research.

-After that you started a centenarian study here in Japan?

Hirose: Yes, in 2000 we conducted a two-year joint study together with the Tokyo Metropolitan Institute of Gerontology (currently the Research Team for Geriatric Pathology, Tokyo Metropolitan Institute of Gerontology). Then in 2002, we carried out a national semi-supercentenarian study on people aged 105 or older, sending letters to over 10,000 elderly care facilities around the country who introduced us to semi-supercentenarians in their care.

-How was that study carried out?

Hirose: We started by doing blood tests to extract genetic information and examine protein, cholesterol, and immune cell levels. Genetic analysis using external genome databases has allowed us to get closer to understanding the mechanism of aging and the limits of the human lifespan. We also conducted one-on-one interviews with participants to learn about their health and lifestyle.

-Is this the data that became the foundation for the Center for Supercentenarian Medical Research?

Hirose: Yes, that’s correct. I was contacted by the dean of the School of Medicine about building a comprehensive supercentenarian medical research center right here at Keio, which for me was a dream come true. The center is currently focused on the study of what we call supercentenarians, which refers to people aged 110 and older, and we have organized a consortium with Saitama Medical University and other universities across the country to compile data from supercentenarian autopsies. For research on this extremely special group of seniors to yield useful results, it is extremely important for us to be able to compare their data with that of people with average lifespans. That’s why we have senior assistant professor Yasumichi Arai leading a wide range of epidemiological studies on the elderly.

-What kind of things have you learned about centenarians through your research so far?

Hirose: Well, the first things we learned were that senescence, or the cellular damage caused by aging, is a contributing factor to chronic inflammation and that life expectancy beyond 85 is largely determined by a person’s “frailty.” Frailty here generally refers to things like unintended weight loss, slower walking speeds, and decreased physical activity. People who exhibit these symptoms tend to have shorter life expectancies. But something else we learned through our interviews is that many centenarians feel a genuine sense of happiness. I'm still researching this phenomenon with a group of psychologists, but I think that many of these long-lived individuals have developed ways to cope with stress. And this is obvious when you meet one of them—all of the centenarians we’ve spoken with have warm, charming personalities and plenty of stories to tell.

-Please tell us a little more about your aspirations for the Center for Supercentenarian Medical Research.

Hirose: It’s amazing just how comprehensive centenarian research has become. We are now able to integrate expertise from across the university in disciplines like medicine, genetic engineering, psychology, and economics. In fact, no other research institution has amassed as much information on centenarians and supercentenarians as we have here at Keio. That said, there are still many fascinating supercentenarian research topics yet to be explored. I would like to take this opportunity to encourage young and early-career researchers to join us in solving the mysteries of aging and longevity.

-Could you talk about the purpose of your epidemiological research on 85-year-olds?

Arai: Well, simply put, centenarians are the products of the lives they’ve lived. When we try to trace their longevity back to particular factors once they’ve reached 100 and older, we run up against memory loss and other cognitive limitations. That’s why we’re working with slightly younger generations—in order to reveal the mechanisms of healthy aging as these individuals journey toward becoming centenarians.

In fact, there is still very little epidemiological data on individuals in their eighties, which happens to be the average life expectancy here in Japan. That’s why we want our research to be comprehensive and highly interdisciplinary, involving specialists from fields like medicine, psychology, sports medicine, and social welfare.

-Could you elaborate on your current epidemiology research at Tonomachi Town Campus?

Arai: We currently use a facility at Kawasaki Municipal Hospital to carry out large-scale, longitudinal studies into the physical and mental health and daily lifestyles of 1,000 healthy, independent 85- to 89-year-old residents of Kawasaki. In fact, we have just completed studies on 900 different individuals. Our studies will continue in the long term, but I hope to announce some of our findings by 2025, when baby-boomers will be in their late seventies and early eighties.

-What kinds of tests and examinations do study participants usually undergo?

Arai: In addition to blood samples, blood pressure analysis, and hearing tests, we also measure participants’ walking speeds to assess the state of their muscles and bones. We also conduct spinal x-rays, grip strength tests, and bone density analyses. We know from our results so far that few centenarians suffer from diabetes or clogged arteries and that many have healthy blood vessels, which we investigate meticulously—down to the tiniest capillaries under the nails.

Examining the conditions of bone and muscle is also important in order to prevent fractures, which can cut otherwise long lives regrettably short. In order to prevent dementia, another serious impediment to healthy old age, we ask them in detail about their daily habits and history of illness. On average, it takes two to two-and-a-half hours to examine one individual.

-Having examined so many elderly individuals, how do you envision the future of longevity and a super-aged society?

Arai: I actually think the answer to that question may lie beyond medicine. Everyone experiences physical decline with age, and every supercentenarian has an illness or physical ailment of some kind. But most of them are still quite happy. They accept aging as a natural process and seem to have reached what is sometimes termed “gerotranscendence” in their old age, surpassing the general belief that health is important above all else.

As a doctor, I find myself wishing good health to every person I meet, but the elderly have taught me that there is more to happiness than health alone. I hope to join forces with other experts in psychology and sociology to collectively tackle the next big topic for interdisciplinary discussion—what happiness looks like in a super-aged society.

*All affiliations and titles are those at the time of publishing.

*This article originally appeared as a special feature in the 2019 Winter edition (No. 301) of Juku.