All of us hope to live a healthy, happy, and long life, and die peacefully in our beds. However, living for 100 years or more is an achievement only a small portion of us can claim.
So, how and why have those lucky few broken the century barrier? We take a closer look at the research.
It’s well known that the average human lifespan has increased in recent centuries and even decades. We know we are likely to live longer than our parents. This is largely because of rapid advances in medical science and improvements in public health.
However for most of us, there’s a catch. While the average lifespan for people over 65 has increased, the number of ‘healthy years’ hasn’t kept up.
Chances are, for many of us, this longer life will be accompanied by spending a greater proportion of our later years in ill-health.
Scientists call this the difference between your ‘lifespan’ (how long you live) and ‘healthspan’ (the period of your life that is free from disease).
They estimate the average difference is about nine years. That means, we are typically likely to spend nearly a decade living with one or more disabling chronic disease such as heart or lung disease, cancer, diabetes, osteoporosis, or dementia. In most cases, those conditions will be present in the last years of our lives.
Chronic diseases are a barrier to many of us reaching the 100-year milestone.
In contrast, there is some evidence that people who live to advanced ages have different patterns of chronic disease to their counterparts with shorter lifespans.
As medical researchers phrased it in the title of their influential 1999 article, “The older you get, the healthier you have been”.
Studies show centenarians generally have excellent health right up until the end of their lives, with fewer medications, hospital visits, and illnesses.
It’s not that they don’t get the same chronic diseases and die from them—most do—but about half of them don’t get these diseases until two or three decades later than most people. That means the difference between their 'lifespan' and 'healthspan' is about the same as those who live shorter lives.
In about one in seven cases, centenarians remain disease-free their whole lives. Scientists categorise them as ‘escapers’, compared to ‘delayers’ who delay disease onset, or ‘survivors’ who make it to very old age, despite grappling with chronic disease earlier in life.
Interestingly, research shows centenarians don’t share many consistent diet and lifestyle choices—so there’s no magic pill for reaching 100. Some regularly drink alcohol, smoke, and eat chocolate like other people do, while others don’t do these things much.
However, obesity is rare for centenarians, and most have lives filled with constant physical movement in a day-to-day sense, through activities such as walking, cycling, and gardening. They also tend to be optimistic, conscientious, and socially active within their communities. They enjoy life, embrace new experiences, deal well with stress, and remain independent in many ways, building the foundation for a good state of mental health.
These lifestyles are not necessarily enough to guarantee a person will live past 100. Some of us may live happy, active lives but still fall ill and die relatively young.
Centenarians make it further because they are protected from chronic disease by longevity genes. Those genes become most important after 80 years of age, at which point, the people who have them are more protected from chronic disease than the rest of us.
Prior to that, lifestyle, environmental, and even policy factors are more important for staying alive. They include exercise, breathing clean air, and eating well to avoid the onset of heart disease, cancer and other chronic diseases, plus public health measures to reduce child mortality and contagious diseases.
So, for people to live past 80, they need to get through the first 80 years of their life intact first. That applies to people with longevity genes just as much as the rest of us.
The United Nations (UN) estimates there are more than half a million centenarians globally and by 2050 there will be 3.7 million. In Australia, there were around 6,000 centenarians in 2021 and there are predicted to be 50,000 by 2050.
That’s not just because the overall population is growing. Centenarians will also make up a bigger share of the population with time. While fewer than one in ten people aged over 65 are 100 or older now, the UN estimates that proportion will rise to almost one in four by 2050.
Such large numbers prompt the question: if we live well, how many of us have the genetic predisposition to make it past 80? It may be more of us than we think.
One study found nearly a fifth of the general population have genes that give people a 70% chance of living a very long life. That suggests over one in ten people have the genetics to make it to 100 and beyond.
Unlike previous generations, when many people genetically equipped to live to 100 still died earlier from unrelated causes, we’re getting better at preventing those causes of death. That’s why we’re seeing centenarian rates skyrocketing now.
Understanding what factors contribute to people living until 100 gives us insight into ageing potential: how we might live longer, yet stay healthy. This kind of research can help us understand the relationship between ageing and chronic disease—including cognitive decline through conditions like Alzheimer’s disease, which many centenarians do not have.
Brain studies of centenarians who have died provide some insights as to why this is. Some centenarians are Alzheimer’s resistant. This means they haven’t accumulated as much Alzheimer’s-related brain damage as expected given their advanced age. On the other hand, there are centenarians’ that show a lot of Alzheimer’s related brain damage but are cognitively healthy right up until they die. There is still no cure for Alzheimer’s, but centenarian research helps unlock the secrets of protecting against this disease and other forms of dementia as our average lifespan continues to increase.
If you or someone you know is over 100 (or close to it), centenarian researchers would love to hear from you. There are studies happening all over the world, including in Australia. You can find these by searching online or you can contact National Seniors on 1300 76 50 50 if you are a centenarian who would like assistance to participate in a research project on this topic.
For the rest of us—the best strategy for living a longer, healthier life is to stay physically and socially active, and embrace new experiences. You never know, you could be one of the lucky ones who will break the century barrier in the future!