Stress causes us to age biologically faster, but the effects can be reversed

We age biologically when our bodies are stressed, but get younger again when we recover, according to a study that analyzed the DNA of people when they had emergency hip surgery, severe covid-19 or were pregnant .

“This cover suggests that we have the machinery to be able to go back in time at least a bit,” says Jacques White at Duke University in North Carolina, who co-led the study with Vadim Gladyshev at Harvard University.

We normally measure age by the number of birthdays – this is called chronological age. But people can be biologically older or younger than their chronological age depending on factors such as whether they smoke Or get enough sleep.

To measure biological age, researchers have developed “epigenetic clocks” that analyze patterns of markers on DNA called methyl groups that correlate with age.

White, Gladyshev and their colleagues used these clocks to assess the impact of three types of stressful events on biological age. In each case, they analyzed DNA from blood samples taken at multiple points in time from participants in previous studies.

In the first analysis, the team found that the biological ages of nine people with an average age of 81 increased rapidly when they underwent emergency surgery to repair a broken hip, but returned to the preoperative levels over the following week.

Next, the team measured the biological age of 29 people with an average age of 60 while they were hospitalized with severe covid-19 and after they were discharged. The biological age of the female participants dropped after discharge, but not that of the male participants, perhaps because men take on average longer to fully recover of the disease.

Finally, the team compiled data from four studies involving more than 200 pregnant people, which is known to put stress on the body. Their biological age increased during pregnancy, but by six weeks postpartum it was back below the levels seen in early pregnancy.

The researchers also used epigenetic clocks to measure the biological age of mice before, during and after pregnancy and found the same pattern.

In another experiment, the team showed that young mice experienced a sudden increase in biological age after being surgically mated to older mice, so that older mice’s blood flowed into their own circulation. . This was reversed after they were surgically separated from the older mice.

The idea that biological aging accelerates during stressful events but then reverses is consistent with a previous study that found that people’s gray hair sometimes returns to its original color after recovering from psychologically stressful events like marital separation.

However, Luigi Fontana at the University of Sydney in Australia says that while there may be short-term fluctuations in biological age, the general trend continues to age. “Your gray hair may go back to some color, but it won’t go back to the hair you had when you were 10,” he says.

Still, now that we know that biological aging can at least reverse slightly, it raises the possibility that therapies could be developed to push that reversal further, White says.