New Research: Here’s How the Brain Changes Before, During and After Your Period

Updated: May 04, 2024

New research is bringing to light how the brain physically changes while women are on their periods, uncovering insights into a previously uncharted aspect of women's health.

The body’s capabilities are nothing short of remarkable, and for people with a uterus, it’s important to count menstruation among them. For a long time, the scientific community lacked an in-depth understanding of how these processes, particularly hormonal fluctuations during the menstrual cycle, affect the brain. This knowledge gap is finally being bridged by two pivotal studies released in October 2023, revealing the significant impact of periods on brain structure and function.

“The female brain is still massively understudied in cognitive neuroscience,” remarks Julia Sacher, MD, PhD, psychiatrist and neuroscientist at the Max Planck Institute for Human Cognitive and Brain Sciences and the University Clinic in Leipzig, Germany. With such pioneering work from these studies, we inch closer to unraveling the mysteries of the female brain, opening up new possibilities for medical and scientific breakthroughs.

Hormonal influences on brain structure

In a study published in the peer-reviewed journal Nature Mental Health, researchers Dr. Sacher and colleague Rachel Zsido, PhD, set out to map how ovarian hormones, particularly estrogen and progesterone, influence brain structure during the reproductive years. To capture the full scope of these changes, they monitored 27 women across their menstrual cycle using state-of-the-art 7 Tesla MRI scans, blood sample analysis, and ultrasounds.

This study focused on the medial temporal lobe and the hippocampus, critical for memory creation and spatial navigation. These regions are particularly dense with sex hormone receptors, making them sensitive to the ebb and flow of estrogen and progesterone levels. The researchers observed that during the menstrual cycle—when estrogen levels are high, and progesterone levels are low—these brain areas undergo structural plasticity, meaning they physically change and adapt.

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Hormone fluctuations and the brain

A separate research team took a different angle, investigating how the cyclic changes in the hypothalamic-pituitary-gonadal (HPG) axis affect the brain. This study has yet to be peer-reviewed but is available on bioRxiv.

The HPG axis is a network of hormones and glands orchestrating the menstrual cycle and influencing everything from mood to fertility. The study focused on understanding how these hormonal changes impact three crucial aspects of brain structure: White matter microstructure, cortical thickness, and brain volume.

White matter serves as the brain’s internal communication system, containing fiber tracts that connect different brain regions. Efficient white matter means better, faster brain communication. Cortical thickness refers to the thickness of the brain’s outer layer, which is involved in higher-level thinking and processing. The study found that hormones like estradiol, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) directly impact these structural components. For example, higher levels of FSH are associated with increased cortical thickness, suggesting a more robust capacity for processing and cognition during certain phases of the menstrual cycle.

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In conclusion…

These studies mark significant progress in understanding how the menstrual cycle’s hormonal fluctuations intricately affect the female brain, but there is still more research to be done on how this directly impacts behavior—and this, in turn, can lead to more effective healthcare for women everywhere.

“Even though sex steroid hormones are powerful modulators of learning and memory, less than 0.5% of the neuroimaging literature considers hormonal transition phases, such as the menstrual cycle, the influence of hormonal contraceptives, pregnancy, and menopause. We are committed to addressing this fundamental research gap,” concludes Dr. Sacher.

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