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The increase in life expectancy is decreasing
Oct
After more than a century of steady progress, new research warns that the rise in global life expectancy is slowing, largely because improvements in early-life mortality have already been achieved.
Test: Cohort mortality projections show signs of slowing growth in life expectancy. Photo credit: puyalroyo/Shutterstock.com
Growth in life expectancy in high-income countries may slow over time, particularly because of the slower pace of improvement in mortality at very young ages, according to a new study published in the journal “Life expectancy gains in high-income countries.” PNAS.
Constantly increasing uncertainty
Advances in public health, medical science, and socioeconomic structure have significantly increased life expectancy in high-income countries over the past century. However, whether this upward trend will continue in the future or slow down over time is an ongoing debate.
Many studies estimating human lifespan have used a period approach, which is a synthetic measure reflecting the average mortality risk observed in a given calendar year. This approach can help assess adverse mortality trends, but cannot provide clear evidence on longevity trends.
On the other hand, the cohort approach to life expectancy captures the actual survival experiences of a specific group of people born during the same period, offering a direct measure of longevity.
To predict the near future of human longevity trends, researchers from the Max Planck Institute for Demographic Research, INED, and the University of Wisconsin-Madison recently estimated life expectancy in a cohort of generations born between 1939 and 2000 in high-income countries, using multiple mortality projection models.
Tracking life expectancy trends
Scientists estimated the life expectancy of current generations in 23 high-income, low-mortality countries using six different models predicting age-specific mortality rates. In particular, the researchers focused on generations born between 1939 and 2000, using data from the Human Mortality Database.
In addition, they performed an age distribution analysis (which quantifies the contribution of different age groups to changes in life expectancy in the cohort over time) to identify the main factors influencing projected trends in life expectancy in the cohort.
The increase in life expectancy has slowed
The research results for all forecast models showed a slowdown in the increase in life expectancy in the generations born in 1939–2000.
In terms of previous longevity trends, the study found that the average rate of improvement was about 0.46 years per birth cohort between 1900 and 1938, meaning each subsequent generation during this period lived longer than the previous one. This roughly equates to life expectancy increasing from about 62 years for people born in 1900 to about 80 years for people born in 1938, although the article does not provide exact numbers.
Such dramatic improvements in life expectancy over a few years appear to decline by 37% to 52% for generations born between 1939 and 2000, depending on the methods used to forecast. In an optimistic scenario where the previously observed steady improvement in life expectancy remains unchanged, those born in 1980 could expect to reach the cohort life expectancy milestone of 100 years.
However, the current findings point to a different scenario in which none of the generations analyzed in the study are expected to reach this milestone.
The rapid decline in the infant mortality rate in the early 20th century, resulting from advances in medical science, improved sanitation, and higher living standards, was found to have contributed significantly to the significant increase in life expectancy. In the late 1920svol In the 20th century, infant and child mortality was already extremely low, which led to a slower rate of improvement in mortality at very young ages. This pattern is strongly linked to the recent slowdown in life expectancy growth.
The study found that more than half of the projected slowdown in life expectancy is attributable to under-5 mortality trends. At the same time, more than two-thirds can be explained by mortality trends among people under 20 years of age.
As the researchers noted, improving midlife mortality could lead to significant increases in life expectancy. Similarly, advances in clinical practices that specifically address the underlying causes of age-related mortality, as well as improvements in behavioral risk factors, could significantly delay the onset of aging in humans. However, current findings suggest that, at least for current generations, even significant improvements in mortality rates are unlikely to reverse the projected slowdown in life expectancy.
Existing research highlights declines in life expectancy in the United States and other developed countries, reflecting deeper economic and social factors that highlight the complex interaction between social conditions and health outcomes.
The results of the current study indicate that this decline is not just a periodic phenomenon, but also a generational-level phenomenon that may be influenced by a combination of biological and social factors. Together, these findings point to a broader decline in the rate of increase in human lifespan.
Changing the shape of policy and planning
The survey results provide important information for policymakers preparing for the future. However, it is worth mentioning that unpredictable or unexpected events, such as future pandemics or epidemics, dramatic changes in the social or economic structure, or medical breakthroughs, may significantly change projected mortality trends as well as the rate of increase in life expectancy.
Because the study focuses on populations rather than individuals, the observed long-term decline in life expectancy growth could have implications for people’s approach to saving, retirement and long-term care. While the authors highlight broader policy implications, such as the need for governments to adapt social and health systems, both governments and individuals may need to adjust their expectations and plans for the coming decades.
