The new study is intended to influence how future research on pain is conducted and can lead to more effective therapies for chronic pain.
A new study by researchers from Montreal and Toronto challenges the ancient myth that men are harder at dealing with pain than women.
The study found that while women are slightly more sensitive to physical pain in general, men remember that more deeply and are more likely to be more stressed in dealing with the same pain in the future. The results should revolutionize the field of pain research and lead to better treatments for chronic pain.
"What's interesting about it is that if you were to guess the existence of a sex difference here, almost everyone – including me – would have guessed otherwise," said Jeffrey Mogil, a professor in McGill's psychology department. University and co-author of the study.
"Men must be stoic and macho and women do not need to be, so if anyone will admit to being stressed on the second day, it should be women. But it was not. It was the men.
The researchers experimented with laboratory and human rats and observed similar results.
The researchers experimented with laboratory and human rats and observed similar results. The researchers applied low levels of heat to the hind paws of rats. For the 41 men and 38 women, the heat was administered on their forearms.
To make the pain more memorable, the rats soon after received an injection of vinegar intended to cause stomach pain for about 30 minutes. Human guinea pigs used a tightly inflated blood pressure cuff and exercised their arms for 20 minutes, experiencing a short but excruciating pain.
The next day, humans were inflicted with the same levels of pain, but men rated heat pain higher than the previous day and higher than women. Researchers observed the same perceptual differences on the second day in male vs. female rats. The results were published this week in Current Biology.
"Or is it that men are remembering (the pain) and women are not, or are they remembering, but only in men is this memory that causes stress," explained Mogil.
The results suggest that memory plays a role in chronic pain.
"This is an important finding because growing evidence suggests that chronic pain is a problem as far as you can remember, and this study is the first time this pain is demonstrated using a translational approach – both rodents and humans" . said Loren Martin, the first author on the paper and assistant professor of psychology at the University of Toronto Mississauga.
"If remembered pain is a driving force for chronic pain and we understand how pain is remembered, we can help some sufferers by treating the mechanisms behind the memories directly."