I envy researchers whose topics are close to the general public. When I try to explain my research (brain oscillations) to a lay acquaintance, I begin with very general information about brain electrophysiology. However, before I even get to the part where my research starts, the person is gone (mentally or literally). In contrast, one of my colleagues studies women's health. She can easily do a TED Talk or a Science Slam, and at least half of the audience will relate. And I relate as well. So I picked up a book partially out of curiosity, partially to be able to meinen Senf dazugeben when talking to a lay audience. The book is “Demystifying The Female Brain: A neuroscientist explores health, hormones and happiness” by Dr Sarah McKay. Note: There seems to be a new version of the book with updated evidence. I read the 2018 version.

There are many beliefs about women's brains and related behaviour. Some of them are slight misconceptions, while others are plain fabrications. Most of them boil down to hormones. Indeed, hormones play a role, but they are only part of the story.

A set of interconnected structures in the brain and in the body regulates hormonal secretion. This set is termed the HPO (hypothalamic-pituitary-ovarian) axis. The hypothalamus and pituitary gland are located in the brain, specifically on top of the brainstem, while the ovaries are in the lower pelvis. The hypothalamus releases gonadotropin-releasing hormone (GnRH) to stimulate the pituitary gland. The pituitary gland releases luteinising hormone (LH) and follicle-stimulating hormone (FSH) to stimulate the ovaries. When stimulated, the ovaries release oestrogens and progesterone into the bloodstream. Hormonal release is partially regulated via feedback loops. Negative feedback loop: rising levels of oestrogen and progesterone signal the hypothalamus and pituitary to slow down GnRH, FSH, and LH production. Positive feedback loop: a peak level of oestrogen from a mature follicle in the ovary triggers a surge of LH and FSH, causing ovulation. Stress, lack of sleep, or extreme exercise can also influence the hormonal cycle.

Female hormone levels substantially change across the lifespan. In childhood, oestrogen and progesterone levels stay very low and stable before age 10. In puberty, total oestrogen levels increase massively, and progesterone production begins cycling with the first period. During adult years, oestrogen levels change every month, and progesterone rises in the second half of the cycle (luteal phase). In pregnancy, oestrogen and progesterone increase substantially. In perimenopause, hormone levels start to swing. In menopause, oestrogen and progesterone decrease significantly. In postmenopause, oestrogen and progesterone remain consistently low for the rest of life. Nice figure here.

There is no conclusive evidence about the relationship between sex hormones and cognitive performance. However, it has been shown that oestrogen levels in a monthly cycle do not influence performance in mental rotation tasks, verbal fluency tasks, and verbal working memory tasks. Moreover, rodent studies show that oestrogen increases dendritic spine growth, which can be a marker of plasticity. So women can learn, remember, and reason irrespective of their hormonal level.

Sexual desire seems to be affected by sex hormones. In particular, oestrogen increases desire, and progesterone decreases it. One study found that during ovulation, women were more attracted to masculine men rather than “bookish nice guys”. And during other cycle phases or on contraception, women were more likely to choose a “nice guy”. The follow-up studies have been inconclusive, showing evidence for and against the “ovulation shift cad or dad” hypothesis. In any case, it is helpful to keep in mind that effects are small, and many other factors affect the choice of a partner.

There is evidence of a gender gap in depression: women are more often diagnosed with depression than men. Sex hormones can partially explain this gap. Oestrogen was found to improve mood, meaning mental health may worsen if levels of oestrogen are low. Progesterone instead may increase anxiety and the solidification of traumatic memories. Besides sex hormones, the gender gap in depression may be explained by non-hormonal factors: women’s dampened stress response, low self-esteem, higher rates of violence and discrimination.

In menopause, the levels of both oestrogen and progesterone are low, which puts women at higher risk for depression. Perimenopause and menopause are also associated with unpleasant bodily sensations. Here, hormonal replacement therapy (HRT) is a generally safe and effective approach. However, studies have found that taking HRT was protective from cancer and dementia only if the treatment started early after the last period. If the treatment started late (10 years or more after the last period), the effect of HRT may be harmful. However, menopause should not equal deterioration. The grandmother hypothesis is an evolutionary theory proposing the reason why women live long past their reproductive years. It suggests that, by helping feed and care for grandchildren, older women boost their genetic success.

The book contains theories and supporting studies with references. It's easy and quite entertaining to read. However, and the author acknowledges it, only a single point of view is presented. The author is a straight woman and a mother of two children. Hormonal changes during transgender transition and possible side effects of it are not described. And sometimes it feels that the author peddles the message that is comfortable for her. For instance, she cites the study showing that women with one or two children live longer than women with more or no children. The reader is invited to accept the conclusion that pregnancy and motherhood are protective somehow. The study cited indeed found an association consistent with this interpretation, but in this study, researchers didn't ask women whether having children or not was their choice. Women who choose not to have children are very different from those who are not able to have children. So if you are reading this book, you may probably want to think critically and check the references.

Overall, I learned new information. The main conclusion of the book (with which I wholeheartedly agree) is that female hormones change the brain, but so do many other things.

Favorite quote:

“I can only conclude that somewhere between hardly anyone and almost everyone suffers from PMS”

August, 2026