2023-10-13 12:36:57
In women’s brains, regions important for memory and perception are remodeled during the female cycle
Remodeling processes in central learning and memory centers in the human brain take place in harmony with periodic fluctuations in sex hormones. A new study by Rachel Zsido and Julia Sacher from the Max Planck Institute for Cognitive and Brain Sciences and Leipzig University Hospital links rhythmic oscillations of female sex hormones over the course of the menstrual cycle with changes in the temporal lobe of the brain.
Researchers examined women’s brains at six different times during the menstrual cycle.
© MPI CBS
Researchers examined women’s brains at six different times during the menstrual cycle.
© MPI CBS
Sex hormones have an impressive effect as messenger substances in the brain, including when it comes to learning and memory: For example, early menopause can be associated with an increased risk of accelerated brain aging and dementia later in life. However, little is known about the effects of hormonal fluctuations on the brain in early adulthood. In their current study, Rachel Zsido and Julia Sacher show that the body’s own fluctuations in female sex hormones also influence the structural plasticity of the brain during the reproductive years.
The scientists took blood samples from 27 study participants, used ultrasound to examine the growth of the follicles in the women’s ovaries as well as the time of ovulation and zoomed into the deeper levels of the brain using a 7 Tesla MRI. There are many receptors for sex hormones in the temporal lobe and hippocampus, and important cognitive functions of the brain are supported, such as episodic memory.
Individual representation of the respective hormone profile
In contrast to previous studies, Zsido and Sacher examined the women’s brains not just at a specific point in time, but at six different points in time during the menstrual cycle. This longitudinal study design allows a very precise and individual representation of the respective hormone profile. This is important because there are often strong individual fluctuations and the patterns of hormone secretion often vary greatly from woman to woman. Typically, during the 28-day cycle, there is a sharp increase in the hormone estradiol around ovulation, while progesterone dominates the second half of the cycle. Estradiol is one of the most important hormones in the female body and plays a crucial role in maintaining the reproductive system. Progesterone, another important sex hormone, prepares the uterus for a possible pregnancy and has an anti-anxiety, sleep-inducing, relaxing and calming effect.
Similar to ebb and flow, the female brain is attuned to a constant rhythm of hormones, which the study shows for the first time. “We found that certain regions of the medial temporal lobe, which are important for episodic memory and spatial perception, increase in volume under high estradiol and low progesterone levels – that is, these brain areas remodel in synchrony with the menstrual cycle. We want to clarify in various follow-up studies whether these rhythmic changes are altered in people with an increased risk of suffering from a memory or affective disorder,” says Julia Sacher. “In general, the female brain is still far too little studied in neuroscience. Although we know that sex steroid hormones strongly influence our learning and memory, less than 0.5 percent of the literature in this area addresses the menstrual cycle, the influence of hormonal contraceptives, pregnancy and menopause. We want to change that because in order to be able to specifically treat women with Alzheimer’s or depression, we need to better understand how the healthy female brain adapts to changes and is influenced by sex hormones.”
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