How women navigate depends on their menstrual cycles

Women use spatial navigation just before their periods, but rely more on cues from their surroundings during ovulation.

Women favor different memory strategies depending on where they are in their menstrual cycles, new research shows. Asked to navigate a virtual maze, most women who are ovulating will rely on response memory, using cues from their surroundings to memorize turns. Women in the premenstrual phase of their cycle, however, relied on spatial memory, picturing an aerial map of the maze in their heads. We speak with Wayne Brake, one of the study’s authors, about the findings.

ResearchGate: How did your study assess which memory strategy women were favoring?

Wayne Brake: We used a virtual navigation task. Basically, it was like a video game where women had to find their way through a maze. The maze can be completed either by using the cues in one’s surroundings and making a mental (cognitive) map of the area, or by remembering where each maze arm is relative to another, for example noting that you have to skip two arms then take the next arm. Later we remove the surrounding cues and see how well or poorly someone completing the maze does. This allows us to test which memory system they preferentially use.

RG: What did you find?

Brake: We found that during the ovulatory phase when estrogen peaks, women tend to use response memory to solve the maze. Response memory is like basic habitual motor memory, such as turning right then left to get to work. However, when women are in the mid/late luteal phase of the cycle, just prior to menstruation when progesterone peaks and estrogen also rises again, they are more likely to use spatial memory. Spatial memory is what you’d use if you encountered a roadblock on your way to work, and had to mentally pull up a map of the neighborhood to think of an alternate route.

RG: What is the significance of these results?

Brake: While we have known for years that estrogen affects the brain to cause memory bias in female rodents, this is the first study to see how hormones affect women's memory.

RG: Does birth control interfere with these preferences for one memory strategy over another?

Brake: We did not test women on birth control, but I would imagine that it could affect memory bias, depending on the form and dose.

RG: The study included 45 women. Does that sample size affect your interpretation of the results?

Brake: Sample size always affects interpretation of the results. However, the effect was quite big, Cramer’s V=.431, and considering that we found such a large effect, we are confident in these data. We’ve posted details of the effect sizes as a supplement to the article on ResearchGate.

RG: Would you recommend changes to the way studies involving memory tasks are conducted in light of your results?

Brake: I would certainly note that researchers studying memory in women or female mammals should control for hormone levels.

RG: What led you to look into the effects of hormones on memory bias?

Brake: It's about bloody time that we start understanding more about the female brain. Every mental disorder or disease, every single one, has a sex bias. Yet, we still mostly only study the brains of men. Since researchers began studying the brain, they’ve known that studying the female brain is messy. There was more variability, which people suspect could be accounted for by changes in circulating ovarian hormones, so many people couldn't be bothered with all that extra variability in their studies.

RG: What are the next steps for you in this research?

Brake: We know from studies in rats that once females give birth and raise a litter of pups, they tend to have a bias toward spatial memory regardless of hormone levels. So going forward, we’d like to do another study with this type of virtual navigation task, this time comparing moms with non-moms.

Featured image courtesy of when i was a bird.