Scientists Demonstrate Brain Changes During Menstruation

The fluctuating hormones of the menstrual cycle not only impact reproductive anatomy but also influence brain structure. A recent study sheds light on this brain remodeling process.

A team of researchers led by neuroscientists Elizabeth Rizor and Viktoriya Babenko from the University of California Santa Barbara studied 30 menstruating women to track the structural changes in their brains throughout their menstrual cycles. They meticulously documented these changes as hormonal levels fluctuated.

While the results are awaiting peer review, they are available on the preprint server bioRxiv. The findings indicate that the brain’s structural alterations during menstruation may extend beyond regions traditionally linked to the menstrual cycle.

The researchers noted, “These findings represent the first evidence of simultaneous brain-wide changes in human white matter microstructure and cortical thickness aligned with menstrual cycle-related hormone fluctuations.” They also suggested that hormones might profoundly affect areas of the brain beyond the well-known receptor-rich regions of the hypothalamic-pituitary-gonadal-axis (HPG-axis).

Deciphering Menstrual Cycle Effects on the Body

Given that menstruating individuals experience around 450 menstrual cycles in their lifetimes, understanding their diverse effects on the body is crucial.

Despite affecting half of the global population for a significant portion of their lives, research on this topic has been surprisingly limited. The reasons behind this lack of research remain largely unknown, a genuine enigma.

Most studies on hormonal effects on the brain have primarily focused on brain activity during cognitive tasks rather than changes in brain structures themselves.

Rizor, Babenko, and their research team highlighted, “Fluctuations in HPG-axis hormones have significant impacts on behavior, brain structure, and function by influencing the mammalian central nervous system. However, there is limited knowledge about how these hormonal changes affect the structural components and neural pathways of the human brain.”

Hormonal Transitions and Brain Connectivity

During hormonal transitions such as puberty, oral contraceptive use, gender-affirming hormone therapy, and post-menopausal estrogen therapy, researchers have observed changes in the microstructure of white matter—the fatty network of nerve fibers that facilitate communication between gray matter regions.

To bridge the knowledge gap regarding menstruation’s effects on the brain, the team conducted MRI scans on participants during three menstrual phases: menses, ovulation, and mid-luteal. Concurrently, hormone levels were measured at each scan.

The findings revealed that fluctuations in hormones corresponded with changes in both gray and white matter volumes, as well as in cerebrospinal fluid volume.

Specifically, leading up to ovulation, when levels of 17β-estradiol and luteinizing hormone increase, participants exhibited white matter alterations indicative of enhanced information transmission capabilities.

Gray Matter Thickness and Ovulation

Before ovulation, follicle-stimulating hormone linked to thicker gray matter as it stimulates ovarian follicles.

After ovulation, progesterone correlated with an increase in tissue volume and a decrease in cerebrospinal fluid volume.

The implications of these findings for brain function remain unclear. However, this research paves the way for future investigations, potentially shedding light on the underlying causes of severe menstrual-related mental health issues.

“While we haven’t identified the functional consequences or correlates of these structural brain changes yet, our results could have implications for understanding hormone-driven shifts in behavior and cognition,” the researchers commented.

“Studying the relationships between hormones and brain networks is crucial for comprehending daily nervous system functioning, hormonal transition impacts, and changes across the human lifespan.”

Read the original article on: Science Alert

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