Hippocampal volume and affect in response to fluctuating estrogens in menstrual cycle irregularity: a longitudinal single-subject study 2024 Heller+

Abstract

Irregular menstrual cycles, affecting approximately 30% of women in their reproductive years, are often overlooked in research, limiting our insights into the broader spectrum of hormonal interactions. Understanding the relationship between endogenous hormone fluctuations and brain function across the menstrual cycle, particularly beyond regular menstrual cycles, is essential for comprehending mental disorders prevalent in women.

To this aim, a healthy female with an irregular menstrual cycle underwent dense sampling for 5 consecutive weeks, primarily covering the follicular phase and ovulation. Blood draws provided measurements of estradiol, estrone, and progesterone. T1-weighted MRI scans assessed bilateral hippocampal volumes. Positive and negative affect were collected at each session. Statistical analyses included cubic regression curves, Spearman correlations, and mediation regression models to explore hormonal associations with hippocampal morphology and affect.

Significant fluctuations in hormonal concentrations, hippocampal volume, and affect were observed across the 25 testing days. Estradiol and estrone significantly correlated with hippocampal volume, while progesterone showed no significant association. Increasing concentrations of estrogens were linked to decreasing positive affect, mediated by hippocampal volume fluctuations. Increasing concentrations of estrogens were further associated with increasing negative affect, however, independently of hippocampal changes.

Our findings suggest potential roles of estrogens in affect regulation and brain function in a participant with an irregular menstrual cycle. This research serves as a blueprint for future investigations into the complex interplay between sex hormones and structural brain dynamics beyond regular menstrual cycles and establishes a fundamental framework for the advancement of sex-specific precision medicine.

Open access, https://www.nature.com/articles/s44294-024-00023-1

 

This article seems to talk about both the above paper and the preliminary results noted.

How does the brain react to birth control? A researcher scanned herself 75 times to find out

"Hold the morning coffee and meditation: for about 75 days over the span of a year, neuroscientist Carina Heller’s morning ritual included climbing into her university’s brain scanner at 7:30 a.m. and lying perfectly still for an hour and a half — without falling asleep. By her estimates, this has made her the most-scanned woman in science.

It’s not the title she was after. Heller’s goal was to catalogue how her brain changes during her menstrual cycle, with and without oral contraceptives . Her findings suggest that brain morphology and connectivity change daily throughout the natural cycle and are influenced by birth-control pills, according to preliminary results presented at this year’s annual Society for Neuroscience conference."

https://www.nature.com/articles/d41586-024-03368-4

 

I would have thought changes in hippocampal volume just reflected one fluid changes related to oestrogen. I cannot see any relevance to mood.

I don't quite understand how something can be negatively correlated with positive mood and linked to brain signs and also positively correlated to negative mood but not linked.

Maybe if one oddball lady who scans herself 70 times knowing what she is expecting to find will report what she is expecting to find. And maybe if another oddball day does she won't.