'The limits of human longevity have still not been reached,' study suggests

For over a century and a half, life expectancy has steadily increased in the wealthiest countries. Spectacular climbs in longevity have been noted in the 20th Century, correlating with the slump in infectious illnesses and advances in cardiovascular medicine.

However, for some years now, experts have been obsessing over one question: when is this slick mechanism going to run out of steam? In several western countries, gains in life expectancy have become so slight, they are practically non-existent.

Some researchers see this as a sign that we are heading toward a "biological human longevity ceiling" while others estimate that there is still room for improvement.

Looking at national figures alone cannot be a decider. Behind a country’s average life expectancy lies very contrasted, region-specific realities. This is what the findings of our study that was recently published in Nature Communications revealed. Analyzing data collected between 1992 and 2019, it focuses on 450 regions in western Europe bringing together almost 400 million inhabitants.

A European study on an unprecedented scale

To complete our research project, we collected mortality and demographic data from offices for national statistics across 13 western European countries including Spain, Denmark, Portugal and Switzerland.

We began by harmonizing the original data, a task that proved crucial because the regions differed in size, and data offered varying amounts of detail according to each country.

Then we recalculated the annual gain in life expectancy at birth for each region between 1992 and 2019, an indicator, which reflects mortality across all ages. Sophisticated statistical methods allowed us to pick out the main underlying trends, regardless of short-term fluctuations caused by the heatwave in 2003, or virulent, seasonal flu outbreaks between 2014-2015, for instance. 2019 is the cut-off date for our analyses because it is still too early to know whether the coronavirus pandemic has a long term effect on these trends or if it was limited to 2020-2022.

The results we obtained provide us with an unprecedented panorama of regional longevity trajectories across Europe over an almost 30-year period, from which we draw three findings.

First finding: Human longevity has not hit its limits

The first message to emerge from the study is that: the limits of human longevity have still not been reached. If we concentrate on regions that are life expectancy champions (indicated in blue on the chart below), we note that there is no indication of progress decelerating.

These regions continue to demonstrate around a two-and-a-half month gain in life expectancy per year for men, and approximately one-and-a-half month gain in life expectancy for women, at an equivalent rate to those observed in previous decades. In 2019, they include regions in Northern Italy, Switzerland and some Spanish provinces.

For France, Paris, and its surrounding Hauts-de-Seine or Yvelines areas (pertaining to both men and women), featured alongside the Anjou region and areas bordering with Switzerland (only applicable to women). In 2019, life expectancy reached 83 for men, and 87 for women.

In other words, despite recurrent concerns nothing presently indicates that lifespan progression has hit a glass ceiling; prolonging life expectancy remains possible. This is a fundamental result which counters sweeping, alarmist statements: there is room for improvement.

Second finding: regional diversity since the mid 2000s

The picture looks bleaker when considering regions with "lagging" life expectancy rates, indicated in red on the chart. In the 1990s and in the early 2000s, these regions saw rapid gains in life expectancy. Progress was much faster here than anywhere else, leading to a convergence in regional life expectancy across Europe.

This golden age, accumulating a fast rise in life expectancy in Europe and a reduction in regional disparities came to an end towards 2005. In the most challenged regions, whether it be East Germany, Wallonia in Belgium or certain parts of the United Kingdom, life expectancy gains significantly dropped, practically reaching a standstill. In women, no regions in France featured among them, but in men, they included some departments in the Hauts-de-France.

Longevity in Europe is ultimately divided into vanguard regions that continue to progress on one side, and on the other side, lagging regions where the dynamic is running out of steam and is even reversed. We are experiencing a regional discrepancy that contrasts with the catch-up momentum in the 1990s.

Third finding: the decisive role of mortality at ages 55-74

Why such a shift? Beyond age-specific life expectancy, we sought to gain a better understanding of this spectacular change by analyzing how mortality rates have evolved for each age bracket.

We can state that regional divergence can neither be explained by the rise in infantile mortality (which remains very slight) nor by the rise in mortality in the over 75 age range (which continues to decelerate everywhere). It mainly stems from mortality around age 65.

In the 1990s this demonstrated a rapid drop, thanks to access to cardiovascular treatments and changes in risk-taking behavior. But since the 2000s, this upturn has slowed. In some regions, in the last few years, the risk of dying between 55 and 74 years old is on the rise, as shown in the maps below.

This is particularly true for women living in France's Mediterranean coastal regions (indicated in pale pink). It's also the case for most of Germany. However, these intermediary ages are crucial for the life expectancy gain dynamic, because a large number of deaths occur here. Stagnation or a leap in mortality between ages 55 and 74 is enough to break the overall trend.

Even though our study does not allow us to pinpoint the precise causes explaining such preoccupying progress, recent documentation provides us with some leads which should be scientifically tested in the future. Among these are risk-taking behavior, particularly smoking, drinking alcohol and poor nutrition, or a lack of physical exercise, which are all factors that manifest at these ages.

Incidentally, the economic crash in 2008 accentuated regional variations across Europe. Some regions suffered durably seeing the health of their populations compromised, while further growth was recorded in other regions with a concentration of highly qualified employment. These factors remind us that longevity isn’t just about advances in medicine; it can also be explained by social and economic factors.

What's next?

Our report offers a dual message. Yes, it's possible to increase life expectancy. Europe's regional champions are proof of this, as they continue to demonstrate steady growth without showing any signs of plateauing. However, this progress does not apply to everyone. For fifteen years, part of Europe has been lagging behind, largely due to a rise in mortality around 65 years.

Even today, the future of human longevity seems to depend less on the existence of a hypothetical biological ceiling than on our collective ability to reduce gaps in life expectancy. Recent trends lead us to believe that Europe could well end up as a two-tier system, setting apart a minority of areas that keep pushing the boundaries of longevity and a majority of areas where gains dwindle.

In actual fact, the question is not only how far can we extend life expectancy, but which parts of Europe are eligible.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.