Tony Wyss-Coray of Stanford, one of the architects of modern aging clocks, calls the consumer biological age testing market 'the Wild West': no such test has FDA approval as a medical diagnostic tool
Tony Wyss-Coray of Stanford, one of the architects of modern aging clocks, calls the consumer biological age testing market "the Wild West": no such test has FDA approval as a medical diagnostic tool
On September 25, Stanford Medicine published an explainer in which neurobiologist Tony Wyss-Coray, geneticist Anne Brunet, and epidemiologist David Rehkopf laid out what different biological age tests actually measure and why their numbers disagree. By Rehkopf's estimate, many of these epigenetic tests carry a built-in margin of error of about three years, and one of the most rigorously validated drugs against aging actually pushes these clocks in the wrong direction.
Chronological age is the number of years a person has lived. Biological age estimates how fast the body is wearing down and how many years of healthy life remain. Commercial tests sell this number for a few hundred dollars, from a drop of blood, a saliva sample, or wearable fitness data.
The tests disagree because they hold different views of what in the body betrays age. Blood-based epigenetic tests read chemical marks on the DNA of blood cells and know nothing about the brain or the heart. Other tests look for organ-specific proteins in the blood: a brain-derived protein reports on brain aging, not on the body as a whole. A 70-year-old marathoner in excellent shape but with early signs of cognitive decline might get an epigenetic result reading "younger than your passport age" and a proteomic result reading "your brain is older than your passport age." Both numbers are correct; they simply describe different organs.
It was Wyss-Coray's own lab that demonstrated that blood proteins can decode the aging of 11 separate human organs; cardiologist Eric Topol called that work one of the most important aging reports in recent years. His remarks about the market, then, are a recognition from inside the very field that built these tools.
"Right now it's a little bit like the Wild West," Wyss-Coray says. "There are a whole bunch of companies advertising tests, often along with some powder that they want to sell you that has never been tested in humans in a clinical trial."
These tests are sold directly to consumers, bypassing a physician. Rehkopf adds that the tests are slow to reflect changes in a person's life: a shift in habits may not show up in results for several years.
The most uncomfortable example is rapamycin, an immunosuppressant that reliably extends lifespan and delays age-related disease in mice. In humans, at the doses studied so far, epigenetic clocks actually showed a slight shift toward aging. A similar disconnect appeared in April in the RAPA-EX-01 trial: rapamycin combined with home-based exercise did not add strength in older adults, and all four epigenetic clocks tested there failed to show the expected rejuvenation.
"To me, that doesn't mean that rapamycin has nothing to offer for healthspan and lifespan," Brunet says. "It means we still don't fully understand what these clocks are measuring."
Wyss-Coray himself continues to use these clocks, but on different terms than the market offers. For years he has been collecting monthly blood samples from volunteers, building clocks separately for each organ, so that over time he can check whether an intervention worked where it was needed, before disease develops. The number sold for a few hundred dollars is a rough draft of the very experiment he is still running on volunteers.