02/07/2025
A new study has revealed that menstruation doesn't just impact reproductive health—it also causes widespread structural changes across the entire brain. Neuroscientists from the University of California Santa Barbara tracked 30 women throughout their menstrual cycles using MRI scans and hormone tests. They found that as hormones like estrogen, progesterone, and luteinizing hormone fluctuate during different phases of the cycle, brain regions involved in processing and transferring information also change. These changes weren’t limited to areas traditionally linked to reproductive function.
For example, right before ovulation, there was evidence that white matter—the brain's information highway—became more efficient at sending signals. Estrogen-related changes were linked to thicker gray matter, while rising progesterone levels correlated with an increase in brain tissue and a drop in cerebrospinal fluid. While it’s still unclear how these shifts directly affect behavior or mood, the findings point to significant hormonal influence on brain structure that happens month after month. Considering that menstruation is a routine part of life for half the population, scientists say it’s surprising how little research has been done in this area until now. Another 2024 study even found that different phases of the cycle influence not just specific regions but the entire brain, and these effects may vary with age. Researchers say this opens the door to better understanding how hormonal changes affect cognition, mood, and even mental health.
