Dr Karin Modig from the Karolinska Institutet looked at data from more than a quarter of a million Swedes to discover the secrets to longevity.
Humans may be living longer on average these days, but, even so, only a fraction of us will live to see our 100th birthday. Yet the reasons why only a select few people will become centenarians still remains a mystery to scientists.
But the latest work published by myself and my colleagues has just uncovered one factor that may be key to the long lives that centenarians experience. My research team has found that people that live to 100 seem to possess the superhuman ability to avoid disease.
Centenarians are of such great interest to scientists because they may hold the key to understanding how we can live longer – and live longer in better health.
Researchers have long pondered whether one of the keys to a centenarian’s resilience mainly lies in their ability to postpone major diseases, or whether they’re simply better at surviving them. Or, could it be that they avoid certain diseases altogether?
Understanding the answer to these questions would bring us at least one step closer to figuring out what specific factors contribute to longevity.
So, my colleagues and I set out to see if we could find the answers. In two recent studies, we analysed and compared long- and shorter-lived people born in the same year.
The results from the two studies showed that centenarians not only suffer from fewer diseases overall throughout their lives, they also develop them more slowly. They’re also less likely to experience deadly conditions, such as major cardiovascular disease, compared to their shorter lived peers.
The first study included 170,787 people born in Stockholm County, Sweden between 1912 and 1922. Using historical health data, residents were followed for 40 years – either from age 60 until their death, or up to age 100.
We calculated each participant’s risks of stroke, heart attack, hip fracture and various cancers, and compared those who survived to the age of 100 with their shorter lived counterparts.
We found that centenarians not only had lower rates of disease in late midlife, but they continued to have lower rates of disease throughout their life overall.
For example, at the age of 85, only 4pc of those who lived to be centenarians had experienced a stroke. In comparison, around 10pc of those who almost became centenarians – living to ages 90-99 – had experienced a stroke by age 85.
Moreover, despite living longer, their lifetime risk for most diseases never reached those of their shorter lived peers. At the age of 100, 12.5pc of centenarians had experienced a heart attack, compared to just over 24pc among people who lived between the ages of 80 and 89. This suggests that centenarians delay – and in many cases even avoid – major age-related diseases, rather than simply surviving them more effectively.
One limitation of this study is that it only focused on analysing more serious diagnoses of major diseases. But what if the real key to longevity isn’t that centenarians avoid disease entirely – rather, it’s that they’re able to avoid developing serious diseases?
To explore this, we conducted a second study that included 40 different medical conditions. These conditions ranged from mild to severe – such as hypertension, heart failure, diabetes and heart attacks.
We looked at 274,108 participants who were born between 1920 and 1922 and who lived in Sweden. We followed participants for around 30 years – either from the age of 70 until their death or until they turned 100. A total of 4,330 people became centenarians – just 1.5pc of the participants we looked at for the study.
Even after including a wider range of diseases and allowing participants to have more than one health condition in the analysis, our team came to the same conclusions as we did in the first study: centenarians developed fewer diseases – and their rate of disease accumulation was slower across their lifetime.
We also found that centenarians were more likely to have conditions limited to a single organ system. This is a sign of this group’s health and resilience, since diseases that affect one organ system are much easier to treat and manage in the long term.
For instance, while cardiovascular conditions were the most common diagnoses across all age groups, centenarians were less likely overall to be diagnosed compared to their short-lived companions. At the age of 80, around 8pc of centenarians were diagnosed with cardiovascular disease. In comparison, more than 15pc of people who died at the age of 85 had been diagnosed with cardiovascular disease by 80 years of age. The lower rates of cardiovascular disease appear to be central to the centenarians’ extended survival.
Centenarians also demonstrated greater resilience to neuropsychiatric conditions – such as depression and dementia – throughout life.
Although most centenarians eventually developed multiple health conditions, they did so much later in life than non-centenarians – usually around the age of 89. This was thanks to having fewer diseases and a slower rate of disease accumulation.
Notably, non-centenarians typically experienced a sharp increase in the number of health conditions they suffered with in the final years of their lives. But centenarians did not experience this same sharp decline in health – even from their 90s onward.
The secret to a long life?
The finding that centenarians manage to delay, and in some cases avoid, disease despite living longer is both intriguing and encouraging. It shows it’s possible to age more slowly than is typical – and challenges the common belief that a longer life inevitably comes with more disease.
Our findings suggest that exceptional longevity isn’t just about postponing illness but reflects a distinct pattern of ageing. But whether this is mainly due to genetics, lifestyle, environment or a combination of these factors remains unknown. The next step in our research will be to explore what factors predict living to 100 – and how such predictors operate during a person’s life.
Understanding the mechanisms behind healthy ageing in centenarians may offer valuable insights for promoting longer, healthier lives for all.
Dr Karin Modig is an associate professor in epidemiology at the Karolinska Institutet. Her research group, Ageing and Health, focuses on the ageing population, the driving force of longevity and old age health, and the consequences of it.
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