Scientists have found that older people currently retain more youthful abilities than people who were the same age did in previous decades [1].

How miserable are we?

Recent decades have seen leaps in average life expectancy. However, those mostly stem from successes in curbing childhood mortality and infectious diseases. The gains in later life have been more modest, despite all the advances modern medicine has made. Moreover, some research suggests that while people live longer on average, they also spend an increasingly bigger part of their lives with chronic diseases – in other words, increases in lifespan do not translate into longer healthspan [2].

However, some evidence contradicts the idea that we’re just being kept alive for longer in a miserable, disabled state. A new study by an impressive team of scientists from Columbia University, University of New South Wales, World Health Organization, and University College London seems to suggest otherwise. This study is currently published as a preprint and is under review by Nature.

Big differences, especially in cognition

The researchers utilized two large cohort studies from the UK and China: the English Longitudinal Study on Ageing (ELSA) and the China Health and Retirement Longitudinal Study (CHARLS). Both studies have collected massive amounts of health data on participants from different age cohorts.

While most studies in this field have focused on the burden of disease or severe disability, the researchers constructed instead a composite index of intrinsic capacity, “comprising subdomains of cognitive, locomotor, sensory and psychological capacity and a further subdomain labelled vitality, which may represent underlying age-related biological changes and energy balance.”

What they found was that more recent cohorts had much higher levels of intrinsic capacity at the same age. This capacity expectedly declined with time, but the rate of decline was attenuated in more recent cohorts, suggesting slower aging.

The cohort studies from which this data was derived had not run long enough to directly compare distant cohorts: for instance, it was impossible to directly compare the intrinsic capacities of the 1950 (year of birth) cohort and of the 1930 cohort at the same ages.

Where such direct comparisons were possible, they produced hope-inspiring results. For instance, in ELSA, the intrinsic capacity of the 1950 cohort at age 68 was significantly higher than that of the 1940 cohort at age 62. As the researchers note, this comes close enough to validating the popular saying “70 is the new 60.”

The biggest improvements were between the most recent (1950) cohort and the 1940 cohort. “If these directly observed trends were extrapolated to compare the earliest with the most recent cohort,” the authors write, “the improvements would be significantly greater than those we could observe directly.” Among individual metrics, the largest improvement was in cognition.

Whether those trends are equally valid for both sexes remains a question, as the researchers were unable to perform direct cross-gender comparisons. However, within-gender trajectories were largely similar to those found in the overall analyses.

Does this square with previous research?

The researchers admit that interpreting their results is hard due to the numerous factors at play and that those results seem to contradict previous research, which has found that increases in longevity are accompanied by increased prevalence of chronic conditions in older age. The authors then hypothesize at length about possible reasons for that.

For instance, they suggest that the increased prevalence of chronic diseases at a certain age “is likely driven, at least in part, by people who would have previously died from a condition such as heart disease now surviving into older ages.” Not only is modern medicine increasingly better at keeping people with chronic conditions alive, but it can often ensure a reasonably full, active life.

Thus, today, the same disease can be less debilitating than a decade or two ago. There have also been improvements in detection: some chronic diseases that are routinely diagnosed today might have been overlooked more often in the past, creating an impression of lower disease burden.

Variance of measures used across different studies and periods might also be a factor. For example, the researchers note, a common question used to determine the burden of disability is how easy it is for the respondent to use a phone. However, phones today are very different from phones 20 years ago, and using them requires different abilities.

While this study presents a hefty reason for optimism, it also has many limitations, and its findings will have to be validated by future studies, using additional cohorts and designs.

Our research suggests there have been significant improvements in functioning in more recent cohorts of older people in both England and China. Within ELSA, more recent cohorts entered older ages with higher levels of intrinsic capacity, and subsequent declines were less steep than for earlier cohorts. Improvements were seen in all subdomains. Trajectories were similar for males and females and largely consistent across both countries.

Literature

[1] Beard, J., Katja, H., Si, Y., Thiyagarajan, J., & Moreno-Agostino, D. (2024). Is 70 the new 60? A longitudinal analysis of cohort trends in intrinsic capacity in England and China.

[2] Garmany, A., Yamada, S., & Terzic, A. (2021). Longevity leap: mind the healthspan gap. NPJ Regenerative Medicine, 6(1), 1-7.