We’re Just Now Learning How Hormones Affect Our Brains


If you’ve ever found yourself freaking out before a meeting, you’ve experienced shifts in cortisol, the “fight or flight” hormone which plays an important role in general stress regulation (studies have found that burnout and complex grief, for example, have been associated with high cortisol levels).

Mood and energy shifts are likely due to changing levels of progesterone and estrogen, the two primary female sex hormones that also influence mood, cognitive functions and libido.

When you feel a sense a satisfaction from a meal, that’s elevated dopamine, the brain chemical for reward-driven learning, pleasure and satisfaction.

If you hug someone and feel more connected to them, oxytocin — the neurotransmitter and hormone of love, responsible for social connection and bonding as well as trust, herd mentality and social conformity — has increased.

That gut feeling you keep experiencing? It’s likely serotonin — a hormone regulating mood and social behavior that’s mainly found in the intestine — speaking.

Together, hormones influence our level of energy, ability to focus, quality of sleep, experience of stress and anxiety, mood, sociability and cognitive function. For women, hormones also follow a pattern. A month-long pattern. But the physiological process of how hormones manifest in our bodies still isn’t broadly understood, even by doctors. And though we’re beginning to discuss their effects, this conversation is still surprisingly speculative. Often, the subtext is that hormones lead to irrational behavior, that they’re a problem.


Researchers in the field, like Simon Baron-Cohen, author of several studies on gender differences and the brain, admit that the topic of sex difference in psychology is “fraught with controversy” and a field “prone to misunderstanding and misinterpretation.”

“It’s an area people didn’t want to enter for many decades because of its political incorrectness and [risk] of being misunderstood,” but increasingly, researchers are starting to ask more open-minded questions, “without fear of being accused of having a sexist agenda,” explains Baron-Cohen.

Most of our scientific knowledge on the topic of hormones and the brain has been acquired via animal studies — the majority using male animals — which is about as problematic as it sounds. However, new research offers fascinating findings.

In one study, researchers at the Max Planck Institute for Human Cognition and Brain Sciences performed brain scans on a patient for two months and discovered that her brain literally changed every month in sync with her hormones.

“In parallel to the rising estrogen levels leading up to ovulation, the Hippocampus (a brain area essential for memories, mood and emotions) also increases in volume — the volume of the grey matter as well as that of the white matter,” explains Claudia Barth, co-author of the paper.

Only one female was observed in this study; how changes in brain structure affect behavior and specific cognitive ability are still not fully understood.


There are tons of reasons to investigate women’s brains in relation to their cycles aside the obvious, which is that, well, half of the world happens to have a female brain. Here are just a few:

PMDD: This kind of research can help us understand premenstrual dysphoric disorder (PMDD), which affects one in 12 women in the days leading up to her period. PMDD is a more extreme case of PMS and women who suffer from it complain of severe physical and psychological symptoms such as listlessness or mood swings comparable to a depressive episode. “To get a better understanding of this disorder, we first have to find out which monthly rhythm the brain of a healthy woman follows. Only then can we reveal the differences in persons affected by PMDD,” says Julia Sacher, a researcher at Max Planck Institute.

Addiction: Addiction and recovery could be partly modulated by hormonal shifts in the menstrual cycle. Understanding these factors could offer beneficial insights into personalized treatments for recovery.

Per a BioMed study, “Preclinical and clinical research suggests that ovarian hormones (i.e., estradiol and progesterone), which fluctuate over the course of the menstrual cycle, influence smoking behavior, and relapse vulnerability.”

Menopause: Perhaps the most misunderstood and interesting phase of a woman’s life is menopause, which is associated with brain fog and some fifty other symptoms (yes, really).

According to Dr. Marianne D. Legato, a pioneer in the field of gender-based medicine, low levels of estrogen — which tend to occur during menopause — “impair our ability to think clearly and certainly impact memory.”


Birth control: The effect of birth control on both brain and hormones is becoming an increasingly hot topic, with suggestions that it is depressing the hell out of us. The most popular oral contraceptive options prevent ovulation and inhibit the usual hormonal cycle, which has a direct effect on mood-regulating chemicals in the brain, like serotonin. In addition, at least one study has found significant differences between the brain structures of women who did or didn’t take oral contraceptives — although it is not clear yet what those differences might mean.

The rewards of studying female hormones and the brain outweigh the risks of misunderstanding, bad research methods and discrimination. There are so many interesting and important things that happen to our brains which we do not yet understand. Education and information about the menstrual cycle and behavior could enable us to better predict changes, and adjust and adapt. Controversial, yes, but worth it.

Alexi Surtees and Daniele Orner-Ginor are co-founders of Ovary, a community and data company addressing knowledge gaps in women’s health. Learn more here. Illustrations by Maria Jia Ling Pitt. 

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