– By Yayeri van Baarsen –
What’s the link between your menstrual cycle and your brain? More than you might think: your brain is, after all, controlled by hormones. Changes during your cycle are even visible on MRI scans. This is how your hormonal cycle affects your brain.
Scan your brain
Like most medical research, brain studies in the past decades have primarily focused on men. Convenient, because men don’t have ‘inconvenient things’ such as a menstrual cycle or pregnancy that can influence research results. However, that’s precisely the point: those fluctuating sex hormone levels women experience during their cycle do indeed affect their brain. Hormonal fluctuations during the menstrual cycle can lead to changes in the brain areas that are involved in information transfer, memory, behaviour, and – this surely won’t come as a surprise – emotions.
The male body as the standard in the medical world; researcher Carina Heller was fed up with it. Heller decided to use herself as a test subject and had her brain scanned. No less than 75 times. She did this in three different five-week periods: during a natural menstrual cycle, while she was on the contraceptive pill, and three months after coming off the pill. The goal of her study (published in 2024) was to investigate how the contraceptive pill affects the brain. However, the scans of her head during the first period (when she had a natural cycle) revealed that not only her hormone levels changed during her cycle, but also the size of her hippocampus (a brain region essential for memory, storing information and memories, and spatial orientation).
Brain studies
Heller’s research is one of the few in this field, but it’s not the only one. Another study from 2023, involving 27 women with natural cycles, already showed that the volume of the medial temporal lobe (a part of the brain that contains, among other things, the hippocampus) changes during the menstrual cycle. The hippocampus enlarges when estrogen levels increase and progesterone levels decrease. A 2020 study, in which a researcher with a natural menstrual cycle had her brain scanned daily for a month (just like Heller), also showed that the hippocampus changes under the influence of cycle-related hormone fluctuations.
The hippocampus isn’t the only part of the brain affected by your hormones. A study of 30 women by researchers at the University of California (USA), showed in 2023 that fluctuating hormone levels during your cycle lead to changes in your grey matter (brain tissue that processes information), white matter (brain tissue that transmits information to nerve cells), and cerebrospinal fluid (brain fluid which protects the brain against shocks). The women in this study had MRI scans during their menstruation, ovulation, and the luteal phase. In addition, their precise hormone levels were measured. The results: before ovulation, when follicle-stimulating hormone (FSH) levels rise, there is thicker grey matter. Just before ovulation, the volume of white matter increases. And after ovulation, when progesterone levels rise, the amount of cerebrospinal fluid decreases.
Recently, there’s been more attention for women’s health. This also means more research is being done into the link between the menstrual cycle and various conditions. Four recent examples that are related to the brain.
1. PMS
Getting irritated by typing colleagues and screaming at your partner for loading the dishwasher incorrectly. One in three women suffers from PMS, which mainly manifests as mood swings, irritability and difficulty concentrating. The exact cause of PMS remains a mystery, but interaction between fluctuating sex hormones and neurotransmitters in the brain is thought to be the source.
‘Your hormones are playing with your brain,’ says neuroscientist Patricia Clement of Ghent University (Belgium) in the LinkedIn post ‘Het mysterie van de maandstonden en het vrouwelijke brein’ (translation: ‘The mystery of menstruation and the female brain’) in July 2025. Clement aims to solve this mystery using MRI scans. She’ll examine the structure of women’s brains at different points during their cycles, as well as investigate how well different brain areas function and communicate with each other. Clement hopes this will help her connect hormonal fluctuations, brain changes, and PMS symptoms.
Back in 2011, there was also attention for PMS symptoms and the brain. Dutch psychologist and brain scientist Lindsey Ossewaarde used fMRI research to determine that premenstrual sensitivity to stress is visible in the brain. She did this by having women watch scary videos at different points in their cycle, measuring their responses to emotional stimuli, and observing their brain activity.
2. Parkinson’s disease
The 2024 study ‘Vrouw en Parkinson’ (‘Woman and Parkinson’) by Dr. Annelien Oosterbaan demonstrated the impact of hormonal fluctuations in women with Parkinson’s disease (a brain disorder in which nerve cells in the brain gradually die). Almost two-thirds of the 110 participants reported that their symptoms were negatively influenced by the menstrual cycle. A few days before menstruation, symptoms worsened and medication became less effective. A majority of women going through menopause also reported a worsening of their situation.
3. ADHD
Also ADHD symptoms are increased by menopause and therefore linked to hormonal fluctuations. ADHD (Attention Deficit Hyperactivity Disorder) is a developmental disorder characterised by attention problems, hyperactivity and impulsiveness. Sometimes the diagnosis of ADHD isn’t made until menopause because only then the symptoms become severe enough. A study into the relationship between the menstrual cycle and ADHD and mental health symptoms in women with ADHD is running until the end of January 2026. The hypothesis: that problems are higher in the week before menstruation. Research from 2024 also showed that ADHD symptoms worsen during the luteal phase, just before the start of menstruation, and that this is due to hormonal fluctuations.
4. PMDD
PMDD – not to be confused with PMS or PME – stands for PreMenstrual Dysphoric Disorder. It’s a neuroendocrine disorder in which you experience severe negative psychological symptoms every month during the luteal phase (the second half of your cycle). Its precise cause is unknown, but it’s clearly linked to the menstrual cycle. PMDD is an abnormal brain response to normal hormonal fluctuations during the cycle.
Research shows that there are differences between the brains of women with PMDD and those of women who don’t suffer from this disorder. For example, women with PMDD have, among other things, increased grey matter volume and an overactive amygdala. The amygdala is a brain region involved in emotional responses and the processing of fear and stress. Further research is needed to gain a more accurate understanding of the development—and, of course, treatment—of PMDD.
Photo by Keith Tanner on Unsplash.
Period! is an independent, online magazine about all aspects of menstruation. Period! is not intended as a substitute for medical advice. If you’re suffering from medical complaints, always visit your doctor or GP. Editorial articles can contain affiliate links. Sponsored collaborations can be found in the category Spotlight. Do you have any questions? Check our contact page.
Also interesting:
Your cycle affects your… sleep
Your cycle affects your… competitiveness
The Cycle Study
Your cycle affects your… attractiveness
Your cycle affects your… academic performance
