Men may tolerate pain better than women, but new research finds they’re more stressed when it comes to how they remember it.
A new report published this month in the journal Current Biology evaluated how male and female mice and humans perceived pain.
Researchers found that male humans and male mice both remember previous painful experiences clearly, but were more stressed and very sensitive to later pain when they returned to the location where the pain occurred.
Women and female mice, on the other hand, didn’t seem to be as stressed.
Why is studying pain important? Researchers can figure out if a memory of pain is a driving factor of chronic pain. By identifying this, they may be able to help treat what causes people to remember pain.
Males are more stressed about remembered pain
The researchers tested 41 men and 38 women between the ages of 18 and 40. Participants were taken to a specific room where heat was administered to their forearm.
The participants rated the pain on a 100-point scale. Soon after, they wore an inflated blood pressure cuff and exercised for 20 minutes.
The next day, the participants went back to the same room of the initial test or to a different room.
Among the participants taken into the same room as the previous test, the men rated the heat pain higher than they did the day before. Women did not rate it as high.
“There was reason to expect we would see increased sensitivity to pain on the second day, but there was no reason to expect it would be specific to males. That came as a complete surprise,” said Jeffrey Mogil, PhD, senior author and the E.P. Taylor Professor of Pain Studies in McGill’s Department of Psychology and Alan Edwards Centre for Research on Pain.The researchers wanted to confirm that pain was increased due to memories of previous pain, so they injected a memory-blocking drug into the brains of male mice. When they ran the experiment, those mice didn’t show signs of remembered pain.
The researchers said this finding is important because increasing evidence suggests that chronic pain is a problem if you remember it.
This was the first time that remembered pain has been depicted using a model in both rodents and humans.
Perceptions of pain
In the past, experiments on pain were only conducted in males so it was hard to compare pain between both sexes, Mogil said.
Findings from this study show that there are differences between the sexes in how they recall pain.This research also adds more weight to the notion that chronic pain is a memory problem, he said. Doctors can then treat the memory of the pain and not just the pain itself. This can be done with therapy or medication.
For example, memory reframing has been used to treat post-traumatic stress disorder, he said. According to his results, this type of therapy could work for pain as well.The researchers plan to follow up on the research to better understand the anatomy behind why males are more stressed by remembered pain, he said.
The big issue of chronic pain
Chronic pain is a significant health problem that affects about 50 million Americans. That’s more than 20 percent of the adult population.
The new research findings support the idea that how people remember pain can affect later pain, Mogil said. His team was “blown away” to find that the same differences between men and women existed in humans as they did in mice.
“This was a study on pain memory or pain-induced stress,” Mogil told Healthline. “Males remembered pain better than the females and were more stressed by it when they did remember it.”
He pointed out that it doesn’t mean men are more sensitive to pain, but that they’re more stressed when recalling it.
“What was even more surprising was that the men reacted more, because it is well known that women are both more sensitive to pain than men, and that they’re also generally more stressed,” said Loren Martin, PhD, an author and assistant professor of psychology at the University of Toronto Mississauga.
Anticipating and recalling pain
Mogil believes there are a few possible explanations for the differences in stress levels among males and females when it comes to remembering pain.
Dr. Samuel McLean, a professor of anesthesiology, emergency medicine, and psychiatry, and the director of the Institute for Trauma Recovery at the University of North Carolina at Chapel Hill, said the findings of this study suggest that evolution may have shaped how males anticipate recurrent painful experiences differently than women.