It’s no secret that a lucky few seem to glide into old age, the years settling gracefully on their bodies, while others appear to have been dragged through time tied to a metaphorical garbage truck. Biologists have been developing numerous ways to measure the rate an individual ages — often called an accelerated or decelerated “biological age” — and trying to translate it into a heightened or reduced risk of the morbidity and mortality that comes with aging.
There’s been a proliferation of various biological aging clocks, mathematical models that look at things like genetic markers or proteins in your body to make some estimation of an individual’s biological age. Research interest in using these clocks has exploded. In the last five years, thousands of papers on or incorporating the clocks have been published. The paper describing one popular biological aging clock, PhenoAge, has over 1,800 citations alone. One recent study suggested that a reason cancer incidence is increasing among younger adults may be accelerated aging, based on this particular clock.
But as scientists use these clocks to associate biological age with specific health risks, like cancer or dementia, and numerous companies eagerly offer biological age measurements in exchange for hundreds of bucks, it may be worth noting that experts don’t agree on what “biological age” actually is.
