Women less sensitive to pain than men

Women tend to forget pain that they suffered more quickly than men, confirmed a new study in mice and humans, challenging the widely held belief that the fairer sex are more sensitive to pain than men.

The study, by researchers from Canada's University of Toronto Mississauga (UTM), showed that men and women remembered earlier painful experiences differently. While men (and male mice) remembered earlier painful experiences clearly, women (and female mice) did not seem to forget.

When experiencing pain again, men seemed to be stressed and hypersensitive in remembering, but women were not stressed by their earlier experiences of pain. "If remembered pain is a driving force for chronic pain and we understand how pain is remembered, we may be able to help some sufferers by treating the mechanisms behind the memories directly," said lead author Loren Martin, Assistant Professor at the UTM. "What was even more surprising was that men reacted more, because it is well known that women are both more sensitive to pain than men, and that they are also generally more stressed out," Martin added.

For the study, published in the Current Biology journal, the team conducted experiments on both humans and mice where they were taken to specific rooms and made to experience low levels of pain caused by heat delivered to their hind paw or forearm.

Further, human participants were asked to wear a tightly inflated blood pressure cuff and exercise their arms for 20 minutes, while each mouse received a diluted injection of vinegar designed to cause a stomach ache for about 30 minutes.

When the next day the participants returned to either the same or a different room and heat was again applied to their arms or hind paws, men rated the heat pain higher than they did the day before, and higher than the women did.

Similarly, male mice returning to the same environment exhibited a heightened heat pain response, while mice placed in a new and neutral environment did not.