We all know people who seem much younger than their chronological age. As they look into what makes us age, one main metric pops up: a biological aging clock-a measure that reflects your body’s age irrespective of your years on Earth.
One of the most popular aging clocks dives deep into our cells. Rather than a one-off, EpiAge seems to work for multiple organs and tissues, potentially shining light on how aging happens.
The clock’s median error was a measly 3.6 years, meaning that it could gauge a person’s age within 43 months. With more work, Horvath found even more patterns that reflected the age of certain types of cells, such as neurons and blood cells.
“The discrepancy between epigenetic age as estimated by these clocks, and chronological age is referred to as EpiAge acceleration,” the authors said.
“Epidemiological studies have linked EpiAge acceleration to a wide variety of pathologies, health states, lifestyle, mental state, and environmental factors, indicating that epigenetic clocks tap into critical biological processes that are involved in aging.”
The thing is, we don’t know why these different types of aging behaviours happen. When measuring age, we don’t know how aging clocks correspond to these hallmarks. It’s partly why there are multiple aging clocks.
In a new study, published in Nature Aging, Horvath and Dr. Ken Raj at Altos Labs took a first step at linking the epigenetic clock to the hallmarks of aging. The cells didn’t age according to EpiAge, even when tested in other cells.
“The observation that aging begins so early in life is possible because age can now be measured based on the biology of the cell instead of the passing of time,” the authors said.
For aging clocks, “This measurement allows interrogation of the link between age and longevity.” While aging clocks are increasingly becoming mainstream, the question is what exactly each measures. This study is one of the first to link a powerful aging clock to the hallmarks of aging.
“The connection of epigenetic aging to four of the hallmarks of aging implies that these hallmarks are also mutually connected at deeper levels,” the authors wrote.
“The absence of a connection between the other aging hallmarks and epigenetic aging suggests that aging is a consequence of multiparallel mechanisms,” the authors said.