Age truly is nothing but a number, especially since we all age at different speeds. Just because 30 years may gave passed since one’s birth, doesn’t mean their biological age is necessarily 30. “We are as old as we feel — and look,” as an article noted. Basically, just because 30 years may gave passed since one’s birth, doesn’t mean their biological age is necessarily 30. And the reason why the biological ages of two people — both born 30 years ago, say on the same day too — might differ is because their “speed” of aging might be different.

Let’s look at it this way: one, there may be much more nuance to the concept of biological age than we’ve grown up believing; two, from a healthcare perspective, it might be wiser to calculate risks and base medical interventions on one’s “pace of aging” than the number of years that have passed since they were born.

Published this year in e-Life, a new study focused on the latter – suggesting that if we’re able to determine the speed at which one is aging, it can serve as a potential marker for chronic diseases, disability, and mortality — across one’s lifespan.

But in order to grasp the objective, motivation, and even findings of the present study, it might be important to understand its predecessor — a 2015 study involving the same cohort of participants and many of the same researchers. The aim of this study was to determine people’s biological age in a way that reflected how fast — or slow — they had aged. Its researchers calculated the biological age of 1,000 participants — otherwise aged 38 years — by analyzing a wide range of each individual’s biomarkers, including blood pressure, cholesterol, gum health, and lung and kidney function.

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Based on this, the biological age of the otherwise 38-year-old participants appeared to vary between 28 years to 61 years — challenging the definition of biological age as we know it. “The concept of biological age is often thought of as the proportion of an individual’s ultimate lifespan that has elapsed,” David Clancy, a lecturer at Lancaster University’s medical school in the U.K., had written in The Conversation.

The participants had the specific biomarkers measured thrice during the period of the study — at ages 26, 32, and 38. The participants whose biological ages were deemed higher had also experienced a more “rapid pace of aging over the previous 12 years.” The researchers also found those who age more quickly looked older and reported more health problems. This study involved many of the same researchers and the same cohort of participants

For the recent study, the researchers measured the participants’ biomarkers again, at the age of 45. The endeavor was to “come up with a ‘pace of aging’ score that converts all those health variables into a single measure that reflects whether a person is biologically aging one year for every year on the calendar, or whether they’re aging slower or faster,” explains an article by the Duke University.

The question that most people might ask, at this point, is: why is this relevant? What is the point of calculating the speed at which one is aging, and how does it benefit humankind?

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“Age is the major risk factor for more than 75% of the mortality suffered by those aged over 64… including cancers, circulatory and respiratory illness, and neurodegeneration. The traditional view is that each of these many conditions [has] their own particular causes,” Clancy explains. However, he says, “the view of biogerontologists, who study the biology of aging, is that there are a few causes of aging which substantially contribute to all of these age-related conditions. According to this view, if just a fraction of the billions spent on researching individual conditions were spent on finding and treating the basic causes of aging, the payoffs could be huge, not least in terms of extended productive (tax-paying) lifespan and reduced healthcare costs.”

Basically, calculating one’s nuanced biological age and pace of aging can serve to calculate one’s vulnerability to different health conditions — creating an opportunity for early intervention, either in the form of treatment itself, or preventions based on risk factors.

In other words, rather than investing in research about individual health conditions, it might be more prudent to fund studies that focus on figuring out how to hinder the process of aging, which is what contributes to the conditions.

As Daniel Belsky, an assistant professor of epidemiology at the Columbia University, who was the first author of both the 2015 study and 2022 one, said, “Together, these measurements can help us understand the factors that drive accelerated aging in at-risk populations and identify interventions that can slow aging to build aging health equity.”