New research by University of Alabama at Birmingham researcher Robert Sorge, Ph.D., and team published today in Nature Neuroscience online challenges the common belief that males and females process pain in the same way.

The majority of existing research shows that men and women have different sensitivity to pain — women are more sensitive to pain overall — but the assumption has always been that a common pain circuit exists in both sexes that is altered by circulating hormones like estrogen.

Sorge and colleagues from three laboratories in the United States and Canada found that this assumption may be false, and that males and females may use very different biological systems to process pain. The key sex difference appears to be in the immune system, and under control of the male hormone, testosterone.