The findings are based on the results of a unique experiment by neurobiologist Karina Heller, who, for scientific purposes, performed 75 brain scans to assess the impact of the menstrual cycle and contraceptive use on brain function. It turned out that taking birth control pills changed the volume and structure of the brain. Now these changes are being studied in terms of the risks and causes of endometriosis, a chronic disease that affects approximately one in ten women of reproductive age.
Women have been taking oral contraceptives for over half a century, but scientists still cannot assess all the risks of taking the drugs. For example, it is known that symptoms of depression and anxiety are reduced in some women and the same symptoms are increased in others. The reasons for this are unclear, so neurobiologist Karina Heller from the University of Minnesota decided to conduct her own experiment, where she acted as both a participant and an observer. The findings are published on the Nature website.
In the first phase, she had 25 brain scans over five weeks to collect data at different stages of her menstrual cycle. A few months later, she started taking the pill and had another 25 scans. Finally, she stopped taking the pill and had a final 25 scans three months later. In addition to the brain imaging, Heller had blood tests and filled out an emotional questionnaire.
The observations showed changes in brain volume and connections during a normal month and while taking the drugs. In the latter case, the indicators were reduced, although this does not directly mean a decrease in brain function. Notably, after discontinuing the drugs, the changes quickly reversed, indicating significant adaptability of the brain.
In terms of hormonal changes, higher levels of estrogen have been shown to affect the functionality of certain brain networks. Progesterone has the opposite effect. These findings led Heller to compare her data with those of women with endometriosis. Further research should show whether these hormonal changes could be the cause of severe chronic disease.