Endometriosis, a disease found in up to 10% of women, has been enigmatic since its first description. A new theory developed by researchers at Simon Fraser University suggests that a hitherto neglected hormone – testosterone – plays a vital role in its development. The research could have direct effects on the diagnosis and treatment of the disease, signaling hope for women with endometriosis around the world.
The disease is caused by the growth of endometrial tissue outside the uterus, usually in the pelvic area, where it contributes to pain, inflammation, and infertility. But why some women get it, and others don’t, is unclear.
The new research is based on recent findings that women with endometriosis developed, as a fetus in their mother’s womb, under relatively low testosterone conditions, compared to women without endometriosis.
According to the researchers’ theory, this low testosterone “ programs’ ‘the developing reproductive system of women to exhibit the unique set of traits associated with endometriosis, including first menstruation, short menstrual cycles, high sensitivity to pain, high inflammation and altered levels. hormones that control ovulation and the menstrual cycle.
The researchers found their theory to be supported by a remarkable range of data in the literature, from genetics and development to endocrinology, morphology, life history and evolutionary biology, thus providing the first full explanation of traits associated with endometriosis.
The theory can explain almost all of the symptoms of endometriosis as downstream effects of low testosterone early in life. The results are presented in two recent articles published in Evolution, medicine and public health, and Scalable applications.
“Low testosterone levels early in development is the strongest known correlate of endometriosis, and its effects can explain the majority of symptoms in endometriosis,” says Bernard Crespi, professor of biological sciences at SFU, holder of ‘a Canada Research Chair and co-author of work with Natalie Dinsdale. “Additionally, the new theory has direct implications for the diagnosis and treatment of endometriosis.”
Crespi notes that testosterone has apparently been overlooked in endometriosis studies because it is generally considered a “ male ” hormone, although it is also known to have key effects in women.
âIt’s very common for researchers to focus on estrogen as a female hormone and testosterone as a male hormone, but in reality these are two hormones of critical importance in all humans,â Ben says. Trumble, assistant professor at the School of Human. Evolution and Social Change at Arizona State University, which was not associated with these studies. âI applaud the authors for going beyond this binary hormonal blind spot and for studying the full range of steroids that can impact women’s health.
This work establishes endometriosis as a developmental endocrine disorder, with roots early in life. It also clarifies the relationship between endometriosis and polycystic ovary syndrome, a disorder caused by prenatal testosterone levels that are too high rather than too low. We show that polycystic ovary syndrome is essentially opposed to endometriosis in its causes, correlates and main symptoms. As such, this work should help transform our understanding of the two disorders. “
Bernard Crespi, professor of biological sciences SFU
Dinsdale, N., et al. (2021) The evolutionary biology of endometriosis. Evolution, medicine and public health. doi.org/10.1093/emph/eoab008.