Common knowledge has it that we think with our brains. But more and more research is coming out to suggest that we actually think with our entire bodies. A new Arizona State University study, for example, has illuminated the connection between the brain and the uterus. Yes, that's right: The uterus has been shown to affect people's cognitive abilities.
It's already well-established that hormones originating from the reproductive system can affect the brain. A lack of estrogen, for example, can lower the magnesium levels in your brain, which in turn can lower serotonin levels and lead to mood swings. However, not that much research has been done on the effects of the uterus specifically. That's what Heather Bimonte-Nelson, professor of psychology at Arizona State University, and Stephanie Koebele, a graduate student at the same school, wanted to find out.
"In the past few decades, there has been a significant amount of research on hormones coming primarily from the ovaries, such as estrogens and progesterone, including how they influence brain and body systems outside of reproduction, such as cognition," Bimonte-Nelson tells Bustle. "In fact, most research has focused on the ovary-brain connection, and little research has been dedicated to understanding the role of the uterus outside of reproduction. In fact, endocrinology textbooks have described the non-pregnant uterus as 'dormant,' 'quiescent,' and 'useless.' Evolutionarily, it does not make sense that a single organ or body system has just one sole function."
To figure out what additional functions the uterus might have, Bimonte-Nelson and Koebele divided lab rats into four groups: some had their ovaries removed, some had their uteruses removed, some had both removed, and some had nothing removed. Six weeks later, they taught the rats to navigate a maze and tested how well they were able to locate specific platforms.
"We believe there is a uterus-ovary-brain triad that might impact brain functions such as memory."
The rats with only their uteruses removed had trouble with this task, frequently looking for platforms where there were none. Yet none of the other rats experienced this problem — not even the ones that had both their ovaries and uteruses removed. The researchers also found that these rats had different hormone levels in their blood than those that had received no surgery.
The ovaries of the rats that got the hysterectomies were the same as those of the other rats, suggesting that it was the removal of the uterus itself that led to these differences. These findings corroborate those of a previous study in Neurodegenerative Diseases showing that women who received hysterectomies had a higher risk for dementia.
The new findings suggest that "surgical removal of the uterus alone can impair some types of memory in the short-term timeframe, two months after surgery," says Bimonte-Nelson. "These results show a unique negative effect of hysterectomy alone on memory and indicate that the uterus is part of a system which communicates with the brain for functions such as cognition. We believe there is a uterus-ovary-brain triad that might impact brain functions such as memory. Although the reason why hysterectomy impacts cognition is not yet understood, we believe hysterectomy yields a unique disruption in this whole system that is different than the disruption that occurs with removal of just the ovaries."
The surgeries performed on the rats intentionally followed the same procedures as surgeries performed on humans, so the study may carry implications for people considering getting hysterectomies. These surgeries are sometimes performed on those with conditions like fibroids, uterine prolapse, cancer, or endometriosis. However, because the study was on rats, we can't say for sure if people would experience the same effects. In addition, since this effect was found about two months after the hysterectomies were performed, the authors plan to conduct additional research to see whether it lasts.
More than anything, these results should be a jumping off point to ask more questions about our reproductive anatomy and how it impacts our brains, says Bimonte-Nelson. "I hope this research inspires others to become interested in learning about the complexity of women’s health across the lifespan."