Stress increases biological age, but normalizes when it disappears
Stressful situations such as emergency surgery or suffering severe covid-19. accelerate biological agein humans and in mice, but that situation is reversed when the situation has been overcome.according to a study published this Friday in the journal Cell Metabolism.
These changes occur in relatively short periods of timea team, coordinated by Harvard and Duke Universities (USA), using various epigenetic clocks of aging, found.
Although traditionally it has been believed that the biological age of organisms increases steadily over the life spanit is now clear that it is not indelibly linked to chronological age.
Individuals can be Biologically older or younger than their chronological age implies. and there is increasing evidence in animal models and humans that the former can be influenced by disease, drug treatments, lifestyle changes, or environmental exposures.
“This finding of a fluid, fluctuating, and malleable age. calls into question the old conception of a unidirectional upward trajectory of biological age over the life span“said one of the authors of the research, James White of Duke University. Previous studies had already pointed to the possibility of short-term fluctuations in biological age.but whether these changes were reversible and the triggering factors had not been studied so far.
Epigenetic clocks to quantify aging.
The team used epigenetic clocks (molecular analyses to quantify aging quite accurately) of DNA methylation, which is a chemical reaction in the body whereby small molecules of methylium are attached to DNA, which can change the way genes are turned on or off.
The clocks used were created from the observation that methylation levels at various sites in the genome change predictably over chronological age. Using this technique, the researchers measured changes in the biological age of humans and mice in response to various stressful stimuli.
In the case of mice, pairs of 3- and 20-month-old animals were joined in a procedure known as heterochronic parabiosis, which surgically joins the blood circulations of the two. The results revealed that “biological age can increase for relatively short periods of time in response to stress.but this increase is transient and tends to return to baseline after recovery from stress,” the journal notes.
The team hypothesized that other natural situations could also trigger reversible changes in biological age. Thus, they observed that transient changes also occurred in humans and mice during major surgery, pregnancy and severe covid-19. In the case of a emergency surgical intervention the patients experienced a strong and rapid increase in biological agebut in the following days this process was reversed and age was restored to baseline values.
Similarly, pregnant women experienced postpartum recovery of biological age at variable rates and magnitudes, and an immunosuppressive drug called tocilizumab improved recovery of biological age in convalescent covid-19 patients. Although the study highlights a hitherto underappreciated aspect of the nature of biological aging.In their study, the researchers recognized some limitations in their ability to probe the connections between short-term fluctuations in biological age and trajectories of biological aging across the life span.