As per a study published in the journal Cell Metabolism, the biological age of people as well as mice, rapidly increases in response to various types of stress, which is then reversed after the stress has passed.
Numerous independent aging clocks indicate that these changes take place over relatively brief periods of time like days or even months.
James White, a co-senior author of the study, says that “This finding of fluid, fluctuating, malleable age challenges this longstanding conception of an upward trajectory of biological age over life’s course. Previous reports have suggested the possibility of short term fluctuations in biological age, but the question of whether such changes are reversible has, before now, remained unexplored. Critically, the triggers of tgese changes were also unknown.”
Although it was once believed that organisms’ biological ages increased steadily over the course of their lives, it is now known that this is not always the case.
It is possible for people to be biologically younger or older than their chronological age suggests.
Furthermore, mounting evidence in both human and animal models suggests that, in addition to other factors, diseases, drug treatments, lifestyle changes, and environmental exposure can all affect one’s biological age.
Co-senior author Vadim Gladyshev, goes on to point out that “Despite the widespread acknowledgment biological age is somewhat malleable, the extent to which it undergoes reversible changes through our lives and the events that trigger such changes remain unknown.”
In one series of experiments, the scientists performed a procedure known as heterochronic parabiosis in which they surgically joined pairs of mice that were three months old and twenty months old.
According to the findings, biological age may rise briefly in response to stress, but this rise is only temporary and tends to return to baseline after the stress has subsided.
First author of the study, Jesse Poganik, explains that “An increase in biological age after exposure to aged blood is consistent with earlier reports of detrimental age related changes upon heterochronic blood exchange procedures. However, reversibility of these changes, as we observed, hasn’t yet been reported. From this initial insight, we theorized that other naturally occurring situations may also trigger reversible changes in biological age.”
As expected, pregnancy, major surgeries, and severe COVID infection in both humans and mice all caused temporary changes in biological age.
For instance, after emergency surgery, trauma patients’ biological ages increased significantly and quickly. But in the days after surgery, this rise stopped, and biological age returned to its initial level.
Similar to this, postpartum biological age recovery occurred in pregnant subjects at varying rates and convalescent COVID patients taking the immunosuppressive medication tocilizumab experienced improved biological age recovery.
Gladyshev says that “The findings imply severe stress increases mortality, at least partly, by increasing biological age. This notion suggests that mortality may be decreased by reducing biological age and the ability to recover from stress could be an important determinant of successful aging and of longevity. Finally, biological age may be a useful parameter in assessing stress and its relief.”
Even though this study sheds light on a previously underappreciated facet of biological aging, the researchers are aware of some significant limitations, so further research is in order to completely cement its findings.