Women are generally more sensitive to physical pain than men. This has been known for ages, but it has never been actually understood why this is the case. Now, scientists at Georgia State University have discovered new evidence about the neurological differences between female and male brains, which may hint at why women have a lower threshold of physical pain than men. The study has been published in The Journal of Neuroscience, and its findings could help develop better anesthesia practices in the future and reduce painful, and potentially traumatic, experiences of female patients.

More active microglia in the female brain

   Microglia are the brain's immune cells. They trigger a defensive response against infectious agents, such as prions and bacteria or viruses, releasing inflammatory chemicals to fight the intruders. Graduate student Hillary Doyle, who participated in the study, highlights that women on average (according to previous empirical studies) need two times the amount of morphine used in men to have the same pain-relieving effect.it hurts!

   Scientists decided to test the hypothesis that this disparity is caused by the brain's immune cells. Running experiments with female and male mice, where their microglia cells were ‘turned off’, scientists discovered that both sexes displayed similar pain experiences in response to opioid painkillers. This suggests that the immune cells are more active in the pain processing regions of the female brain compared to the male brain, playing a role in the gender disparities in pain perception.

   If this translates to humans, it explains not only the disparities in physical pain experiences but also possibly why women are more susceptible to chronic pain conditions like fibromyalgia, migraines (in adulthood; boys are slightly more affected prior to and during puberty), osteoarthritis, neuralgias, and others. Specialist in behavioral neuroscience, and assistant professor at the Neuroscience Institute of Georgia State University, Dr. Anne Murphy—one of the study's co-authors—points out that these findings suggest that future pain drug development should target the microglia cells in order to improve pain-relieving efficiency.

   It is not uncommon for certain medical procedures to become painfully traumatic experiences to patients owing to doctors' inability to administrate a sufficient amount of anesthetics. This is very commonly heard in the dentistry field. This is one field where accounts of traumatic procedures due to insufficient pain relief are not rare, so it could greatly benefit from the insights of this study.