The hormonal fluctuations that characterize the menstrual cycle influence not just reproductive organs but also the brain itself. A 2023 study sheds light on these processes.
Research led by Elizabeth Rizor and Viktoriya Babenko at the University of California, Santa Barbara, monitored 30 women throughout their menstrual cycles, noting changes in brain structure in accordance with hormonal shifts.
According to findings published in a peer-reviewed study, it’s suggested that structural changes in the brain due to menstruation may extend beyond traditional areas linked to reproductive functions.
“These results are the first to document simultaneous brain-wide changes in white matter microstructure and cortical thickness in relation to menstrual cycle-driven hormone variations,” the researchers stated.
They also pointed out, “Strong interactions between the brain and hormones may reach beyond the well-known receptor-dense areas of the hypothalamic-pituitary-gonadal axis.”
Menstruation involves experiencing about 450 periods over a lifetime, so grasping its effects on the body is vital.
However, despite impacting roughly half the global population for a significant part of their lives, research on this topic has been somewhat limited. The reasons behind this are not entirely clear; it’s honestly a bit puzzling.
Most studies have concentrated on how hormones affect neural communication during cognitive tasks, rather than examining the structural changes themselves.
“Cyclic shifts in HPG-axis hormones have profound behavioral, structural, and functional effects due to their impact on the central nervous system,” the research team noted. “Yet, we know very little about how these fluctuations influence the structural components and information pathways in the brain.”
The microstructure of white matter—comprising the fatty fibers that transmit information across gray matter regions—has been shown to change due to hormonal variations such as puberty or the use of hormone therapy.
To explore the gap in understanding about menstruation, the team utilized MRI scans during three menstrual phases: menses, ovulation, and mid-luteal. During each scanning session, they also monitored the participants’ hormone levels.
The findings revealed that as hormone levels changed, so did the volumes of gray and white matter, along with cerebrospinal fluid. Notably, just prior to ovulation, brain changes indicated quicker information transfer when levels of certain hormones rose.
A specific hormone, follicle-stimulating hormone—which increases before ovulation and supports ovarian follicles—was linked to thicker gray matter.
On the other hand, progesterone, which rises post-ovulation, was connected to increased tissue and a drop in cerebrospinal fluid volume.
While the exact implications for individuals remain unclear, this research lays the groundwork for future studies. It might even help illuminate the roots of severe period-related mental health issues.
A separate 2024 study by an international research team found that each menstrual phase uniquely affects the brain, with changes that also relate to an individual’s age.
“Although we haven’t detailed the functional aspects or effects related to these structural changes yet, our findings could offer insights into how hormone-driven alterations affect behavior and cognition,” the researchers concluded.
“Studying brain-hormone interactions across networks is key to comprehending daily human nervous system functioning, particularly during hormonal transitions and throughout life.”
The research is documented in Human Brain Mapping.
