The constant ebb and flow of hormones that drive the menstrual cycle doesn’t just affect reproductive anatomy. They also reshape the brain, and new research shows how it all happens.
A team of neuroscientists led by neuroscientists Elizabeth Reesor and Victoria Babenko of the University of California, Santa Barbara, followed 30 women throughout their menstrual cycle, documenting in detail the structural changes that occur in the brain as hormones cycle.
The results, which have yet to be peer-reviewed, suggest that structural changes in the brain during menstruation may not be limited to those regions associated with the menstrual cycle.
“These results are the first to point to simultaneous, whole-brain changes in human white matter microstructure and cortical thickness that coincide with hormonal rhythms driven by the monthly cycle,” the researchers write.
Menstruating women will experience about 450 periods in their lifetime, so it would be nice to know the different effects they can have on the body. However, even though it is something that happens to half of the world’s population during half of their lives, research on this topic is lacking.
Most of the research on hormonal effects on the brain has focused on brain communication during cognitive tasks, not on the structures themselves.
Research has found that the microstructure of white matter changes with hormonal changes, including puberty, use of oral contraceptives, sex-affirming hormone therapy, and estrogen therapy after menopause.
To address the menstrual gap in scientists’ understanding, the team took MRI scans of their subjects during three menstrual phases: ovulation and mid-luteal phase. During each of these scans, the researchers also measured the participants’ hormone levels.
The results showed that as hormones fluctuate, so does the volume of gray and white matter, as well as the volume of cerebrospinal fluid.
Just before ovulation, the participants’ brains showed changes in white matter that indicated faster transmission of information. Follicle-stimulating hormone, which increases before ovulation and helps stimulate ovarian follicles, was associated with denser gray matter, while progesterone, which increases after ovulation, was associated with increased tissue and decreased cerebrospinal fluid volume.
This research lays the groundwork for future studies and perhaps an understanding of the causes of uncommon but severe mental health problems associated with the menstrual cycle.
Source: Science Alert
