PMS: Poor Memory Syndrome

High estrogen levels during menstruation may inhibit learning

October 5, 2010

Man, women have it hard.

Let’s forget about lower pay rates, and how some women will go through nine months of pregnancy and a painful childbirth.

Instead, let’s look at a woman’s closest companion: her period. (Yes, I’m a guy and I’m really talking about this.)

You probably already know about the side effects of menstruation (watch Chef’s take on South Park). However, you may not know about a recent study in rats that suggests the high levels of estrogen women experience while menstruating may interfere with their ability to learn during that, um, period.

Researchers at Concordia University compared the “latent inhibition” of rats with low estrogen levels to rats with high estrogen levels. Latent inhibition is believed to be an integral part of learning — it enables humans and some other species to better interact with their environments by ignoring irrelevant stimuli while developing important associations with relevant stimuli. To visualize it, think about your annoying younger brother and how he would constantly repeat your name until you entertained him. Now think about that wonderful moment when you were finally able to unconsciously ignore his calls as if he weren’t there. That’s latent inhibition at work.

In the study the rats were initially played a tone unconnected to stimuli. Once the rats became accustomed to the original tone and ignored it, researchers started playing another tone followed by electro-shock treatment. Turns out that the rats with high estrogen levels took longer to associate being shocked with the tone — their hormones actually decreased their latent inhibition and disrupted their ability to form new memories!

A previous study (warning: high jargon level) found that estrogen affects one’s ability to pay attention, and now we see it may also affect learning? Damn.

Men: you better feel lucky. Women: you’ve possibly earned a novel excuse for not finishing your work.

About the Author

Joseph Castro

Joseph Castro has a B.S. in physics and a certificate in professional writing from the University of Hawai’i at Manoa. As an undergraduate he hunted for extra-solar planets but found that research was not for him, leading him away from the telescope and to the pen. Joseph has written about science for the University of Hawaii Sea Grant College Program and is excited to spread out to other venues and share his love of science with the rest of the world.



Randy says:

Hey Joey,

very nice topic and article I must say. I was just wondering who you talk to at Concordia University, and are we both speaking of Concordia University in Montreal?

Thanks for your time.

Joseph Castro says:

Hi Randy,

Yes, the study was done at Concordia University in Montreal ( at the Center for Studies in Behavioral Neurobiology). I personally did not interview anyone for this blog (just did research), but if you are looking to speak to someone about it, you may want to contact Matthew G. Quinlan as he is the first author of the paper I linked to.


Wendy Heath says:

Hell, I’ve known this for years. You can go back through my high school tests, and see a direct correlation between being on my cycle and my test scores. I *always* scored lower when I was on my period- often I’d go back over the test when it was handed back and think “How the hell did I come up with *that* answer?” Interesting to see it demonstrated in rats with some operant conditioning…

Natalie Quiniola says:

Great article, thanks! I have been using PMS as an excuse for years but can now cite this study to back my claim. I’m curious though… are you the annoying younger brother who sought constant entertainment? lol I think not!

Jasmine Castro says:

LOL yay an excuse not to do work! Great article! :D

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