What you probably already know: More than 50 million Americans live with chronic pain, and the number climbs every year. Studies have repeatedly shown that women are disproportionately impacted — they’re more likely to experience chronic pain in general compared to men, and for longer — but scientists haven’t been able to explain why. A new study by researchers at Michigan State University suggests it has nothing to do with pain perception, but rather differences in men’s and women’s immune response.
Why it matters: For the study, 245 people who had experienced traumatic injuries (mostly car crashes) rated their pain levels. Men and women reported equal pain severity on the first day, but overall, men experienced pain for a shorter duration than women. Blood tests showed the men had higher levels of interleukin-10, a molecule that signals neurons to switch off pain. Interleukin-10 is produced by immune cells known as monocytes, which scientists found to be more active in men due to higher testosterone levels. In lab tests with mice, the team found that pain resolved faster for males than females, and when male sex hormones were suppressed, the outcome was reversed.
What it means: The chronic pain disparity between the sexes has caused women to endure negative stigma (and untreated physical discomfort) throughout history, but this study quashes the idea that pain resolution can be controlled through mental fortitude. Rather, the disparity is biological, and women’s chronic pain should absolutely be taken seriously. The immune mechanism for shutting pain down is simply slower in women. The discovery could improve pain management and healing — if immune cells were manipulated into producing more interleukin-10, chronic pain could become a problem of the past without the use of potentially harmful or addictive drugs.
What happens next: The number of chronic pain sufferers has increased in recent years, especially post-pandemic. Federal data showed that about 21% of U.S. adults experienced chronic pain in 2021. Just two years later, the rate surpassed 24%, with 25.4% of women being more likely to have chronic pain compared to 23.2% of men. The discovery that pain resolution is an immune-driven process could help shift scientists’ focus away from how pain starts to why it persists and how it can be calmed by boosting the body’s natural response. In the future, treatment could take the form of topical, non-opioid therapies like testosterone patches that could trigger monocytes or even mimic the interleukin-10 that they produce.
