NOEL KING, HOST:
Women who abuse opioids often get started when they're prescribed medication. Now, that's in part because women are more likely than men to seek help for pain. Researchers are studying differences in pain perception, and they're finding that women may be more adept at discerning pain than men are. NPR's Patti Neighmond has the story.
PATTI NEIGHMOND, BYLINE: This is the pain lab at the University of Florida.
ROGER FILLINGIM: Are you ready?
LUCIA MADEY: Mm-hmm.
NEIGHMOND: Researcher and psychologist Roger Fillingim is testing how much pain volunteer Lucia Madey (ph) feels. He's using a probe about the size of a quarter.
FILLINGIM: It's going to be at a baseline temperature, and then it will heat up to a target temperature very briefly.
NEIGHMOND: Each time the probe heats up, Madey rates her pain on a scale of zero to 10.
NEIGHMOND: Fillingim has been doing research like this for years, asking women and men to rate their pain.
MADEY: It's hot.
NEIGHMOND: The findings, he says, are consistent in his studies and in other pain research.
FILLINGIM: Women report the same stimulus to be more painful than men do.
NEIGHMOND: For pain researchers like Fillingim, pinpointing how and why men and women respond differently to pain is an important first step toward finding more effective treatments.
FILLINGIM: We may ultimately need pink and blue pills. But in order to get there, we need to understand what the mechanisms are that are female-specific or male-specific so that we can design more personalized therapies that are going to help reduce pain for women and men.
NEIGHMOND: Which would be a welcome development, says psychologist Carolyn Mazure with Yale School of Medicine, who says despite so many advances in medicine, women experience more painful conditions than men.
CAROLYN MAZURE: Women are more likely to have, for example, chronic headache. Women are more likely to have lower back pain, neck pain. So whether or not women report pain more or have pain more, I think we could say that both may be true.
NEIGHMOND: And when women go to the doctor, studies show they're more likely to be prescribed opioids than men. Mazure says this can be especially dangerous.
MAZURE: That progression from substance use to addiction is more rapid for women than it is for men. We know that with regard to opioids, cocaine, alcohol, even smoking tobacco.
NEIGHMOND: In fact, federal data show more men die from drug overdose than women, but the rate of death among women is accelerating faster than among men. Mazure says that understanding the why behind differences in pain perception may be critical to coming up with better treatments. As it is now, pain researchers like Fillingim can only speculate. One reason, he says, may have to do with sex hormones.
FILLINGIM: Women have both higher levels and fluctuations in circulating estrogens and progesterone, and those may contribute to experiencing higher levels of pain, whereas men have higher levels of testosterone, which in some studies has been shown to be protective against pain or associated with lower pain sensitivity.
NEIGHMOND: It could also have to do with women's susceptibility to anxiety, depression and sadness, all of which increase sensitivity to pain. Now, one question researchers are starting to look into is whether transitioning from one sex to another makes a difference in how people perceive pain. There aren't many studies, but Fillingim points to one.
FILLINGIM: Individuals transitioning from male to female tended to experience more pain after the transition, whereas going in the other direction, from female to male, there weren't many changes in pain after the transition.
NEIGHMOND: It's a fascinating new area of study, he says, one that will likely become increasingly important in coming years.
Patti Neighmond, NPR News.
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