Almost half of the world’s population will menstruate approximately 450 times in their lifetime. However, there is very little research on how hormonal fluctuations affect brain structure. Most research on this topic has focused on brain communication during cognitive tasks. ” Cyclical fluctuations of hypothalamic-pituitary-gonadal axis (HPG axis) hormones exert potent behavioral, structural, and functional effects on the mammalian central nervous system » note the researchers of the new study, which has not yet been peer-reviewed and is available on the preprint server bioRxiv.

Gray and white matter change volume

The research team performed MRI scans on thirty women with normal menstrual cycles in three phases: menstruation, ovulation and mid-luteal period. The results show that the volume of gray and white matter in the brain changes with hormonal fluctuations, as does the volume of cerebrospinal fluid. For example, follicle-stimulating hormone, which increases before ovulation, was associated with thicker gray matter. Progesterone, which increases after ovulation, was also associated with an increase in gray matter, as well as less cerebrospinal fluid.

The impact of these potential findings on the people concerned remains unknown. In any case, these results could provide a better understanding of the causes of unusual mental health problems associated with menstruation.