The problem with chronological age
Going beyond the simplistic phrase, “you’re as young as you feel,” a recent study highlights that “chronological age” typically doesn’t capture what really matters, in terms of cardiovascular health, cognitive functioning, knowledge, experience, adaptability, and more. These characteristics are not tied to particular chronological ages, rather they vary widely by individual.
This is important because as older people become a bigger proportion of overall society (in high-income countries like the US, Japan, Germany and Italy), we need a much better understanding of “ageing” than chronological age provides.
The research team looked at measures of “frailty” as a proxy for “physiological functioning.” They found that by measures of frailty, chronological age is even less meaningful, “The healthiest 10 per cent of the population at age 90 are close to the level of frailty displayed by the median 50-year-old,” and “the healthiest 25 percent of 90-year-olds are in better health than the least healthy 50-year-olds.” It turns out that chronological age as an explainer of frailty is less than 10% accurate.
Other interesting observations from the study:
Age patterns in productivity are context specific and can change over time (for example with experience or changing technology), rather than being a stereotypical “bell shape” where productivity rises and falls according to age.
“Chronological age might not be a good predictor of age-related labor market potential” In other words, with healthy longevity, many people work happily into their late 60s and 70s.
The study’s authors know of no consensus on how to best measure physiological function and its effects on individuals and the economy.
For economic analyses that inform policy and practice, chronological age plays a prominent role in many areas, such as “consumption, time allocation, wellbeing, preferences, labor supply and retirement, educational investment, health, saving, productivity, innovation, entrepreneurship, and macroeconomic performance.”
Implications
How would measures of physiological function be used in policy and practice? Many proposals for making the workplace “friendlier” to older workers strike me as things that workers of all ages need and appreciate: training and career development opportunities, flexible work, carers’ leave, good health support at work.
Perhaps bigger implications are for “workspan.” Want to work into your 70s? Why not, with high physiologically functioning? Should public health have a more ambitious aim around physiological functioning throughout older age?
Rising numbers of older people may be seen as a problem, but if those people maintain good physiological functioning, their numbers become one of the greatest achievements of the 20th century. For one of the study’s authors, this is the foundation of the “longevity economy.”
This study doesn’t tackle specific ways of combating frailty. Other studies find that strength training is one of the engines of healthy longevity precisely because it confronts frailty. Here are three sources:
Health Notes, Late Career Flyer: issue 5, August 27, 2024
Women who do strength training live longer. How much is enough? by Allison Aubrey, NPR March 11, 2024
Preserve your muscle mass (men), Harvard Health Publishing, February 19, 2016
Sources:
ON THE LIMITS OF CHRONOLOGICAL AGE by Rainer Kotschy, David E. Bloom, and Andrew J. Scot, National Bureau of Economic Research
Why an ageing society requires going beyond chronological age (short Linkedin article with highlights of the above study) by Andrew J Scott