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10/27/2025 13:14
How sex hormones influence brain structure
In a complex longitudinal study, an international team of authors led by the Jena psychologist Dr. Carina Heller examines the influence of female hormones over the course of the cycle on the patterns of brain plasticity. The effect of hormonal contraception and cycle disorders such as endometriosis were also taken into account. The results, now published in the journal Nature Neuroscience, show that all brain areas are subject to hormone-related fluctuations and that it is important to look beyond the normal menstrual cycle to understand them.
Morning routine for science: For five weeks, three women and one man had an MRI scan every day after breakfast. After the brain scan, a blood sample was taken and the concentration of the ovarian hormones estradiol and progesterone was determined. The test subjects also answered daily questionnaires about mood and anxiety. With this complex series of measurements, a research team led by the Jena psychologist Dr. Carina Heller, how brain structure changes over the course of the female hormonal cycle. To better understand the influence of hormones, they chose a woman with a regular natural cycle, a woman who takes hormonal contraceptives, a woman with endometriosis and a man whose hormones are not subject to cyclical changes. Additionally, the team looked at the freely accessible 28andMe data set of another woman with a typical menstrual cycle.
The natural fluctuations in sex hormones control the menstrual cycle in women throughout the entire fertile phase of life. Since the brain is also equipped with sex hormones, it is also subject to corresponding changes. These had never been examined in the entire brain, over the entire cycle and with different hormonal constellations. The MRI measurements showed that these changes not only affect individual regions, but the entire brain, including the cerebellum and subcortical structures. “Surprisingly, in all four women, the changes in volume of the brain over the cycle resulted in approximately the same pattern of brain regions. However, how the brain structure of a certain region changes differed significantly depending on the hormonal conditions,” explains first author Carina Heller, who is currently researching as a visiting scientist at the University of Minnesota and the University of California at Santa Barbara.
In women with typical cycles, progesterone in particular determined the fluctuations in brain structure. In contrast, when estradiol is the dominant hormone throughout the cycle – as in endometriosis or taking the pill – it also appears to have a greater influence on structural brain dynamics. Carina Heller: “A central finding of our study is that the brain-hormone connection is not universal, but depends on the hormonal environment. And that when researching this connection we should not limit ourselves to ‘normal’ cycles.”
Because the data comes from very few test subjects, the results cannot be fully generalized. Wider measurements are needed to confirm these results and examine interindividual variability. However, the longitudinal design, i.e. repeated measurements on the same people, makes it possible to uncover individual spatiotemporal patterns that often remain hidden in large cross-sectional studies.
The project began as an individual longitudinal study: Carina Heller wanted to investigate the influence of hormonal contraceptives on the brain and underwent an MRI herself – for a month before she took the pill, during it and after she stopped taking it. A data set from the study now being presented comes from the young scientist herself. “It is my plan to carry out further measurements regularly, preferably until menopause. Because we still know far too little about the influence of hormonal changes on the brain.”
Contact for scientific information:
Dr. Carina Heller
Department of Psychiatry and Psychotherapy, Jena University Hospital
Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, USA
Department of Psychological and Brain Sciences, University of California, Santa Barbara, USA
Carina.Heller@uni-jena.de
Original publication:
Heller, C., Güllmar, D., Colic, L. et al. Hormonal milieu influences whole-brain structural dynamics across the menstrual cycle using dense sampling in multiple individuals. Nat Neurosci (2025).
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In a complex longitudinal MRI study, the Jena psychologist Dr. Carina Heller the…
Source: Michael Szabó
Copyright: Jena University Hospital
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Journalists, Scientists and scholars
Biology, Medicine, Nutrition / healthcare / nursing, Psychology
transregional, national
Research projects
German
