Why we love this episode:
In this episode of The Period Podcast, Dr Clancy speaks to Dr. Bethany Brookshire (otherwise known as Scicurious). They talk about premenstrual syndrome and premenstrual dysphoric syndrome, along with hormones, receptors and taboos. We know many of you will love listening / reading this episode!
Here at BeYou HQ we thought this would be a great episode to share with all of you. Lastly, if you’ve not been following this series of podcasts with us then make sure you go and check it out on your favourite podcast app.
Listen & Learn:
This is Period podcast, episode 11. My name is Kate Clancy and I'm a professor researching periods, how they affect our life, and how our life affects them.
Today I'm opening my episode with a request. I have started a Patreon page in order to gain patrons to help defray the cost of this podcast. Those of you who have been a part of this podcast from the beginning know that I've already featured some of the most insightful activists, academics and inventors on the topic of periods and menstrual cycles. It turns out that between the audio equipment, editing costs and hosting services, it's expensive to run a podcast. Please consider a monthly donation to help me continue to make great content and feel free to suggest some patron bonuses. Just go to patreon.com/periodpodcast2.
This week, I got to interview/hang out with one of my favourite people Scicurious, also known to regular mortals as Dr. Bethany Brookshire. We became friends many years back and ended up tag teaming not only science online events, but wrote complimentary blog posts on the same articles to offer our disciplinary perspectives. For whatever reason, what we tag-teamed on the most was the study of premenstrual experiences. So we're going to use those pieces as jumping off points today to discuss PMS and PMDD.
The first article we discussed is one by Dr. Matthew Gillings. His main hypothesis is that the hostility in PMS evolved to drive away infertile suitors since women with infertile partners would be cycling far more often than those with infertile ones. The second article was by Dr. Andrea Rapkin and colleagues. In this paper, they contend that there are significant brain differences among women with PMDD and healthy controls.
Let's get to the interview.
Yeah, I don't think I've ever asked you, how did you come up with the name Scicurious?
To be perfectly frank, it was because I was young and immature. Scicurious as a name is an example of how my humour works, which is entirely based in me being unintentionally very clever and other people thinking it's intentional and my entire career has been based on this. So I was like, Scicurious, that's so funny. It's like vicarious, but with science and everyone's like Scicurious, that's so clever. I'm like, "I know, right?" But, really, it was really very stupid.
I mean, I wasn't actually planning on asking these questions, but I'm kind of curious now, what made you decide to start blogging all those years ago?
Well, let me set the scene for you. The year was 2008. I was in my third year of grad school. Have you ever experienced the 30-year slump or had one of your student-
Yeah. Where you pass your calls and you feel like from here on out, all you have to do is do the research. Well, doing the research is hard. So, I went through the third year slump, nothing was working, I began to doubt my life choices and I went to a seminar and lunch thing with Alternative Careers. And there was a writer there, an editor, I think, from Scientific American. And I sat at his table and I asked him if I could write for Scientific American. And to his credit, he did not laugh in my face. He said, "Oh, you should go start a blog. That's what you should do." And so he gave me the name of Boris Isaković. I'm sure you know about-
Yeah. And I got converted, I became a blogger and I blogged on my own site for a little while. I got recruited into science blogs. After that, I actually did start writing for Scientific American, so that worked out. And during that time-
Yeah, I think we joined the network at the same time, didn't we?
We did. Yeah. And during that time, I also got my Ph.D. I did a postdoc. And my blog was pretty popular, partially due to me being unintentionally funny, and partially, because I think I wrote about a lot of things that people weren't necessarily writing about. So then after my postdoc, the funding ran out. I applied around for academic jobs.
I got a job offer for a one-year part-time faculty position at a college that will remain nameless. The job was a 3:3 teaching position with half research and half service with no startup, for $25,000 a year, and they hoped I had another job.
Wait, a 3:3 teaching load was considered a part-time job?
And that's why the college will remain nameless.
And I said no, and when I turned them down, they told me that I was making a huge mistake. I decided to be a freelance writer. And then I got the awesome job offer from Science News and Society for Science & the Public, and here I am.
And what kind of writing do you do for Science News?
I write a couple of things. So science news, I continue my blog, Scicurious. It's a lot less frequent than it used to be and I've changed the focus, so, now I don't blog. I used to blog three times a week, which was a lot and did light things like single papers or single studies. Now, I tend to do in-depth. I still do cover single studies once in a while, but I'm focusing more on what we call a peek behind the science curtain. So I'll combine several studies together. I'll look at how studies or findings might affect research as a whole. I look at life in research from a scientific perspective, that sort of thing.
But my most of my time is spent at Science News for students, which is our middle school arm. It's a completely free online magazine for anyone ages 12 and up and we publish the same science news as every other science magazine out there, except it's written, so anyone 12 years old and up can read it. And I run an educational blog there called Eureka! Lab, where I teach people of middle school age to run experiments, not just demos, but to actually run experiments and do statistics. And I talk about doing science at the middle and high school level, and it's really fulfilling.
I know I've read some of those pieces that you've done like you've done a cookie science one in terms of teaching experimentation.
That was like 18 parts. It was huge.
Yeah. So what are some of the favourite experiments that you've taught in the middle grade reading or writing material?
Well, we've got one coming out, actually, in January. Keep an eye out. We're starting a video series, the Eureka! Lab video series where I'll be doing videos where I design experiments and they'll be accompanied by blog posts to get all the details and the first one's going to be about snot because who doesn't love snots?
I love snots.
Boogers are awesome.
Boogers are great. We use fake snot, but it's still pretty cool.
Now you cover a really diverse range of science and like you said, you do science writing for adults as well as science writing for kids, but your background is in Neuroscience. Can you talk a little bit about the kind of research that you did before you transitioned to being a science writer?
Sure, yeah. Technically, it's not really Neuroscience. My degree is in Physiology and Pharmacology, but I studied drug abuse, literally. I studied psychostimulants. So, I got my Ph.D. looking at the long-term effects of drugs like Ritalin on mouse brains and how they changed the functioning of reward and affective systems in the mouse brain. And then in my postdoc, I switched a little bit and looked at the long-term effects of antidepressants, and how they affected the mouse brain. It was really awesome. And I do miss the mice sometimes. But yes, I've never in my life studied periods. I did perform vaginal swabs on both monkeys and mice at one time, but that's the closest I've ever gotten to the reproductive system.
Wait, what? I didn't know this about your background. Now, you have to tell me about why you were swabbing the vaginas of monkeys and mice.
Well, the monkeys was because I was doing a rotation. A lot of times grad students when they start in graduate school, they'll do rotations with various labs to find out where they fit. And my first rotation was in a monkey lab. And we took vaginal swabs from the females every day to chart their menstrual cycles, just as a matter of course. They were very used to it. You'd go up and you'd take your little swab and you tap the edge of the cage and she would just come over and lift your tail and there you go. They got rewards.
Rhesus macaques, then?
They were Cynomolgus macaques.
And they always got grapes or apple slices for putting up for science. And the mice, we were also tracking the cycle of mice for things like timing for breeding and that sort of thing. We weren't actually studying them as an actual scientific project. It was more like, "Are we breeding this mouse today or not?"
Got it. Okay. See, this is the thing. Not many people know the many different reasons you might find yourself doing vaginal swabs of some sort of animal in the name of science. Now, you do have one other side gig in terms of science, outreach and communication, your Science for the People podcast. Can you tell me a little bit more about that?
Thank you for letting me plug my podcast. Yes, I'm a host on Science for the People. We're a podcast actually based in Canada and this is my excuse to be an honorary Canadian aside from my love of poutine, which is delicious. But Science for the People is an hour-long weekly interview-based podcast, kind of like this one in which we pick topics that always have a science angle, but they also tend to really impact society. And we talk with experts for an hour every week, really going in depth.
So I talk to people who've written really cool new science books or I talk to scientists doing really amazing stuff. And it's a chance to really get deep down into the weeds with an expert, but also to be able to do it in a way that anyone who's listening can understand and I really value that.
All right, so let's get to the topic of premenstrual syndrome because that's kind of where we decided to go for today's conversation because you and I have actually each tag-teamed and covered this topic on two separate occasions. Most recently with this Gillings' article on, oh, what was it on, hostility and infertility and actually several years ago on a PMS/PMDD article that we also covered. So we actually have like this long history of doing this fun tag-teaming thing back when we were doing more blogging. Why do you think we seem to keep coming back to this topic of PMS?
So there's something that I would like to think and then there's something that I really think.
So, what I want to think. I want to think that we keep coming back to PMS because it sucks to have, because it's annoying, and we want to find ways to make women feel better. This is what I want to believe. And there are people I think, who really do want this.
So as an example, Michael Gillings, who wrote that paper hypothesizing that the evolutionary function of PMS was to drive women away from infertile pairings toward more fertile men. He really did actually have good intentions. When I spoke to him. He went on a great deal about how he hates that PMS is the butt of jokes. It's a joke like, "Oh, lady, you're in a bad mood. Do you need a Mitel?" Right? And he said that really made him mad. He said, "It's not funny. I want to normalize this. I want to decrease the stigma."
So, I'd like to think that a lot of people come at it from that. I also think people come at it because there's this overwhelming idea that if our bodies do something and they do it frequently and they do it noticeably, it has to have a point, right? You can't ever just have PMS. it must have a function, right?
If a lot of women suffer from this, there has to be a reason. And so I think a lot of people come back to it trying to keep finding that reason and I find this very funny. I think it kind of stems from a fundamental unwillingness to confront the reality of natural selection.
Because my friend Shannon, she's a developmental biologist, and I love the way she puts this. "Natural selection is not the survival of the fittest. It is survival of the good enough." So, we walk up, right? That's good enough. Lower back pain. Well, it doesn't kill us before we reproduce. It doesn't affect our ability to reproduce, so it sucks and we can have it. Acne, does acne have an evolutionary point?
Evolutionary psychologists would probably say there's something modular in our brains. A module for acne that has some kind of adaptive scenario in which it's good to have. You never know.
I want to know-
Maybe you need to go through this ritual, this teen or young adult ritual, in order to, I don't even know, strengthen your socio-emotional ties to people who will still love you when you have zits on your face. I'm just doing my best to be an evolutionary psychologist here. I don't know if any of that makes any sense.
That was pretty good actually. I would have to say like as someone who suffers from migraine, I would absolutely 100% love to know the evolutionary upside to migraine. It would not make me feel better, but you never know, maybe it would. But the point is not everything has an evolutionary upside, sometimes it's just survival of the good enough.
Right. It's about optimising a bunch of disparate traits that you have to somehow put into this mosaic of an individual.
Right. And PMS is a lot of reactions to hormones, right? You've got these hormones that are surging and ebbing in your body over this cycle and your body is going to react to that in a particular way. Depending on who you are, that reaction may be more or less severe. It doesn't really have to have a point. Maybe that's just me. Why do you think people come back to PMS?
No, I think you nailed it. I think we want to find adaptive scenarios for things even when there aren't any and I think in particular, some of the things that we see in modern life that probably didn't exist to the same degree a long time ago, we're sort of misunderstanding the fact that the modern scenario is really, really different from the ancient one. And not to like oversimplify the whole, "Oh, we have these ancient bodies, but we live these modern lives." I don't subscribe to that all the time exactly, but we do menstruate like 400 times now.
And those folks that don't tend to use some kind of hormonal contraception in order to stop ovulatory cycles are experiencing these surges and withdrawals of hormones at a faster and more extreme rate than people did several thousand years ago who were only having say 50 periods in their lifetime. And so it's such a surprising thing to me when people want to find an adaptive rationale for something about behavioural experiences of the menstrual cycle because the modern behavioural experience of the menstrual cycle bears very little resemblance to the ancient one.
And so, there's all sorts of cool stuff you can say or else I wouldn't study periods, right? Tons of cool stuff you can say about the mechanisms of it, the functioning of it, its variation and what it may mean or the ways in which our lifestyles create that change, but to me, the actual behavioural changes that happen like some things that can happen like premenstrual experiences and stuff, I don't find nearly as compelling and I don't know why people are so in love with it.
Now let's walk through the one that Gillings actually put forth for the rationale behind PMS. You explained it a little bit earlier, but can you go through that again?
Right, so Gillings came at this from the idea that if there's something really significant like PMS going on in a subset of the population, it has to mean something. There has to be a reason and he was particularly interested in PMS, because he noted that in certain societies, particularly I think I'm going to butcher this, the Dogon?
Is that the correct pronunciation?
Yeah, the Dogon of Mali. Sure.
Right. The Dogon of Mali, the women only menstruate about twice a year, maybe on average and when they do, they go into a menstrual hut. And he said, "Well, if a woman is with an infertile man, if she is having no luck conceiving during her fertile phases, she's going to be menstruating a lot more often than twice a year and she's going to be spending a lot more time in that hut. She's also going to be spending a lot more time having symptoms of PMS if she does have those symptoms."
And so Gillings hypothesised that PMS might have evolved as a way to drive away infertile men, so that women could seek out more fertile pairings. So basically, you're super evil at this time of the month, you drive away the infertile guy, and then when you're feeling sweet again, you take up with someone else.
Right. Because you've just shown yourself to be such a worthy mate by being nasty to the person that you're with.
Right. I'm 100% sure that he did not mean it to come across that way.
He meant it as kind of an evolutionary basis, saying, "This is a good function for PMS kind of women reach the breaking point and leave their infertile partner and presumably take up with someone more fertile." This assumes a couple of things. It assumes that women with PMS that that is a heritable condition and it also assumes that PMS symptoms must be correlated with fertility, which I'm not sure it is. I don't know. Do you know if there's a correlation between PMS experiences and fertility?
I don't believe so and given the variability and experiences and the fact that it's so widespread, I would think it would be really, really hard to test.
Yeah. So a lot of the scientists that I called for what we call outside comments. So journalists, science journalists, in particular, we write about a scientific paper. We call scientists who were not involved in the paper and we say, "Hey, what do you think of this?" And hopefully those scientists give us a really honest assessment and say either, "Yeah, this paper is totally awesome and breaking new ground," or they say, "This paper is absolutely horrifying," or they say, "Oh, this paper is kind of cool, but here's my reservations." And that helps us to convey the findings of the paper with good context and with better accuracy. So, I called a bunch of outside commenters about the Gillings piece and they were not particularly optimistic about it. Yeah.
So, certainly my first reaction as you were talking about this infertility thing is wouldn't you see the exact same correlation if it were the woman who was infertile between cycles?
Yeah. There's that. Yeah.
That to me seems like right off the bat, a really big problem. But what were some of the other things that the folks you interviewed had to say?
Well, so one of the reasons that Gillings thought that PMS would help to dissolve infertile partnerships is because based on the idea that a woman would be directing her hostility toward the partner and a couple of my outside commenters noted, "Well, that's not always true." I mean, it can be true just because they can be the thing in the line of fire, but that's not always true. You direct hostility at all sorts of things. It's certainly not necessarily true that hostility is a function of PMS. Maybe you're hostile due to other things. There are lots of things in this world that make me pretty hostile.
You know? So, there's that. And the major thing was, well, there's no correlation between symptoms of PMS and large numbers of offspring. And there's also the fact that women who are unhappy premenstrually a lot of times have other things they're unhappy about. PMS can kind of increase the negative aspect of other things you're going through.
Yeah and in fact, that's some of the stuff that Dr. Jane Usher has done some work on, right? It seemed to me if I remember correctly, that there was this incorrect assumption about her research, right? She found that women who, in certain types of careers that they didn't want, they tended to have worse PMS symptoms. I think people assumed the directionality was like jobs make women unhappy, but really it was like, the jobs were bad. Sorry, PMS makes you hate your job or something like that, but it was really well, no, they didn't want those jobs. They weren't jobs that made them happy. They weren't careers. They were things that they needed to do to earn a wage and so it just was, their PMS was exacerbated in that moment, just like anything is exacerbated if you're unhappy.
Right. It's kind of this tendency to say, "Well, if you're exhibiting something, it must be the PMS." It can't possibly be something rationale that's pissing you off.
Right. So, anything else you want to share? Now, I know this was a couple years ago that we wrote these pieces, but anything else you wanted to share on that particular hypothesis?
I mean, I will say, I think Gillings went to it with very good intentions. He really hated that PMS is a cliché. It's a Dilbert joke. I mean, that's like the worst. He didn't want it to be this laughing matter, because he knew it caused people distress, and he really did want to help to understand it and make it better. It's just that the hypothesis causes some hostility.
As it were.
Yeah. And it also seems like if you are trying to be a good ally to women, maybe not trying to explain their feelings to them would be a good first step. Maybe listening to women and allowing hypotheses to emerge from their lived experiences would be a better move.
Yeah, I think in this case, he was kind of synthesising a body of research rather than trying to explain feelings, but I definitely see your point.
What do you remember of or what can you tell me about how the brain is affected by the menstrual cycle particularly the premenstrual brain?
Yeah. So, first of all, keep in mind that I am not an expert on this.
Sure. So, I may very well get things very wrong. The interesting things about hormones and one of the things I find really interesting about hormones is how incredibly nonspecific they are. Hormones kind of just make it rain, like they're released from a gland and they travel through the bloodstream and so they have effects all over the body. So it's very interesting to me that the hormones during the menstrual cycle, they're surging and they really are surging right before ovulation, you get these massive surges in luteinizing hormone and estradiol and then during the second half, you get this big arch of progesterone. It's really inspiring.
And so you have these big waves of hormones just flooding the body and that means they're also flooding the brain and depending on how sensitive your brain is to these floods of hormones, you can have different reactions. Progesterone and oestrogen, both can affect levels of chemical messengers. We call them neurotransmitters. These are the chemicals that shuttle messages back and forth in between individual brain cells. And so for example, we know that serotonin may be involved in premenstrual syndrome and premenstrual dysphoric disorder.
So for example, we know that depleting serotonin in humans, a lot of people think that low serotonin causes depression because there's been a lot of commercials where Prozac tells you that low serotonin causes depression. That's not technically true. We do know that depleting serotonin in humans will make you very irritable and some of that could be due to the fact that to deplete your serotonin acutely, they give you this amino acid shake that is like a massive load of all the amino acids except for the one that's used to make serotonin and even though they try to flavour it like chocolate mint, it's apparently really terrible. So that might make you a little irritable, but no, it does increase feelings of irritability and people with depression, decreasing serotonin can increase depressive symptoms in some people.
But the interesting thing about serotonin and other chemical messengers is that the effects of serotonin, serotonin doesn't just like smash into a cell. It's a lock and key mechanism, right? So your serotonin is your key and there are receptors on brain cells that are locks and serotonin fits into an astonishing number of locks. There are 14 to 17 known different types of serotonin receptor and they all do different things.
So for example, they think that the serotonin 1A receptor, it's been linked with antidepressant activity, so there are some antidepressants that activate this receptor and that can help in that manner. It's linked with depression and those receptors actually cycle in women, who do not have premenstrual dysphoric disorder, so they cycle with your menstrual cycle. They're sensitive to levels of oestrogen and progesterone. In women with severe premenstrual dysphoric disorder, those receptors don't cycle. They just stay the same, so you have different reactions of those receptors to the levels of hormone that are circulating.
There are other players. Another big one is gamma aminobutyric acid. Friends call it GABA. This is a really big chemical messenger in the brain. It's kind of the main one that we think of when we think of decreasing brain cell activity. It's a truly vast number of actions that GABA has. For example, it's greatly affected by things alcohol. GABA is also one of the neurotransmitters that's associated with anxiety and with anxiety treatments, and it also varies across the menstrual cycle.
Right. With progesterone, right?
With progesterone, yes. So, there are lots of kind of downstream effects of these big hormonal surges that come down to the micro level, these interactions of chemical messengers and just what they're binding to and in what amounts.
Cool. So then, shall we talk a little bit about PMDD then So you mentioned it a little bit there. I think parsing PMS from PMDD would be useful for our listeners and for maybe talking a little bit about this other article that we've covered in the past.
So I'll just say premenstrual syndrome is something that depending on the study, you can say affects somewhere between 30 to 80% of cycling women. And that the way it manifests is incredibly variable. So, that's one of the other issues I kind of have with the Gillings, right? Is that hostility is something that's experienced by some, irritability by some, but there's also a number of other experiences and they're actually very culturally bound. So some cultures you might see nesting behaviours, so someone deciding to clean their whole clean their whole apartment, I wish that was me. Other people who cry a lot around this time, just depending on cultural differences.
So PMDD, though is something very different. Can you say a little bit about how that's different from PMS?
Yeah. But I actually had a question about the culturally bound symptoms of PMS. Can you give examples of-
Cultural incidences where people might have these vastly different reaction?
Oh, gosh, it's been so long since I studied this. Let me think. I mean, one thing I'll do is I'll put in the show notes the article I wrote about it years ago. But my memory of it, I'm trying to think of an article. So one of the other things is that we call it PMS here, but I believe in the UK, they call it PMT, premenstrual tension.
So even in that naming, you can already see kind of a difference and how we're imagining those things. So the word syndrome, right? Syndrome means a collection of symptoms that we don't that we don't totally understand the origin of it and in fact, a lot of other syndromes end up being multiple other things like polycystic ovarian syndrome. It's not just one thing. It might be the same manifestation of symptoms, but the origin is hugely different and the treatment options are different. Obesity, we're now realising is a syndrome because it turns out that its origins are really, really different.
But when you use the term premenstrual tension, we're talking about kind of a different behavioural experience, right? One that's more motivated by stress and anxiety than some of the other symptoms in PMS that you hear about in the United States that are focused not just on some of those behavioural symptoms, but also more physical symptoms. So, cramps and bloating are ones that we talked about premenstrually. I mean, for me, those were always ones that happen menstrually, but they're ones that are often discussed premenstrually in our culture.
There are also other cultures that don't particularly have a name for PMS, but it doesn't mean that they don't have premenstrual experiences and they might have some in common, but when you're experiencing them far less frequently, you're less likely to necessarily put a name to that collection of experiences.
And so one of my goals for season two, I have a couple people in mind already that I'm hoping to get a hold of, is to actually bring some cultural anthropologist in to talk about different experiences of the menstrual cycle cross culturally, because I think that's really where cultural anthropologists, sociologists, historians have a really important role to play in understanding the science of some of this stuff.
That's really fascinating, because when you mentioned that they call it something different in the United Kingdom, it would never occur to me that the culture between North America and the United Kingdom was different enough to actually elicit different symptoms.
That's really fascinating.
Yeah. When I used to teach Evolutionary Medicine, I had a pretty strong component of medical anthropology in it and then we did a lot around culturally bound symptoms, syndromes, rather, particularly ones related to mental health because there are a lot of different diseases or conditions, I would say maybe rather than calling it diseases, that you see just in one country or just in one subpopulation, but not in others.
And so again, that really speaks to how lived experiences are hugely important to the experience of the premenstrual phase, which again, kind of to me puts to question whether we should be looking for adaptive scenarios and heritable traits that produce differential reproductive success around PMS, you know?
Yeah. But yes, you were asking about PMS versus premenstrual dysphoric disorder.
So as you noted, PMS, depending on who you ask, affects between 30 and 80% of menstruating women. Premenstrual dysphoric disorder is where some of those symptoms just really, really stand out and interfere with your life in a significant way. So the symptoms of PMS include things like bloating, fatigue, anxiety, moodiness, breast tenderness, acne, headaches, stuff. And in premenstrual dysphoric disorder, some of these symptoms, particularly things such as anxiety, moodiness, fatigue, and sleep disturbance, those really, really stand out and they interfere with your ability to live your life and this is depending on who you ask, present in 3 to 8% of menstruating women.
And PMDD I think really only came to the four in our kind of public consciousness, relatively recently because it was included in the Diagnostic and Statistical Manual of Mental Disorders in the Fifth Edition. I think a lot of people didn't really realize there was this more severe, kind of clinically relevant version of this until they decided to include it in the DSM V.
Do you remember Sarafem, the drug Sarafem?
Yes, a little bit. Yes.
So that was one of the first times I heard the term PMDD was for commercials for Sarafem, which turned out to just be Prozac. It's the same.
Yes, it's one of the most effective treatments for premenstrual dysphoric disorder is Prozac.
Right, but they gave it a lady name and then put it in a lady commercial, so that women would want to buy it for their PMDD. I remember-
I will say that Sarafem sounds very fluffy and comforting and kind of pleasant. It's a nice name for a drug if you're going to name a drug something.
Sure. One of those striking images that I still remember from that commercial is they had these very over the top, emotional, hysterical women in the commercial like going through different things and then actually dealing with being having animosity often towards their partners, towards their male partners, in these commercials. So there's like this one moment where a woman, I think she's crying at a mirror. And her husband, of course, the sensitive, wonderful man comes up and say, "What's wrong, honey?" And then she's says like, "Get away from me," and throws her hairbrush at him. There's another one where like the woman is hugging a pillow and crying into the pillow.
But what was so interesting to me is just to go back to Gillings one last time before going onto the Rapkin article is that I don't know the extent to which Gillings realises that his own perception of PMS is probably very strongly grounded in his own lived experiences, in his own acculturation and the environment he lives in, right? If the commercial to try to sell you on PMDD is showing these hysterical histrionic women and their supportive male spouses, you're going to develop an idea that PMS is all about hostility and animosity towards male partners and heterosexual relationships, and that this never manifests in any other part of the life.
And also if you're a man, especially if you're a straight man who happens to have a female partner, when you see PMS manifest, it is probably your intimate partner and not the other women in your life because the other women in your life you don't know when they're cycling and they are probably being careful not to display animosity towards you because you're not an intimate partner, right. So, this is one of the things that always bothers me about scientists just in general is how often they don't recognise that their own lived experiences are probably very strongly influencing the kinds of questions they ask and the way that they design their own research.
That's actually something that I wanted to say you've really given me a big awareness of because I am one of those scientists. I am one of those who will go, "I am all about the fleshy, brainy bits. I love fleshy, brainy bits. I want nothing to do with society and culture and I think they have no influence on my work." And that is completely untrue and you have made me realise how very bias I can be coming into my own research, but also, when I'm reading it now, as a writer, I have to just kind of step back really hard and say, "Wait, I need to take a moment and realise I'm coming at this from a very specific perspective that is mine and not somebody else's."
Yeah. As a writer, as a podcaster, right? So, score one for anthropology. Okay, so we've established PMDD is something that affects like a 10th as many women as PMS and the major differences in the severity, right? It's about things that seriously interfere with your quality of life.
And really it can be severe. I mean, there are plenty of women who suffer, well, suffer, experience some symptoms of PMS or PMDD for up to 14 days out of every cycle. That is so much time. That's half your life if you're cycling all the time. I mean, that could be miserable. I have to imagine.
Yeah. Absolutely. So, to get back to that point you made at the beginning, this is a type of suffering, that there's a real need to look into and one of the great things about science is trying to alleviate suffering. So, there's definitely a very, very good reason to study this from a clinical or medical perspective because there is the subset, I mean, a small number but certainly a significant number of women who are having this horrible experience.
Okay. So, a couple years ago, we read an article about PMDD and decided we were sufficiently unhappy with it that we wanted to tag team and cover it together. Can you introduce it a little bit for me?
Sure, the paper was by Rapkin, et al. It was published in Biological Psychiatry in 2011, so, long time ago now.
And it was an interesting study, that I did find it very interesting from the way that they decided to look at things, so it was a neuroimaging study. They did functional magnetic resonance imaging, looking at the involvement of the cerebellum in premenstrual dysphoric disorder, and they looked both with fMRI and they also looked with hormone levels, which I left to you because I'm no good at that sort of thing.
And I left the fMRI to you.
I wouldn't say that I'm good at fMRI necessarily. But yeah, so it was a comparison, 12 controls and 12 women who experienced premenstrual dysphoric disorder. They gave them a whole bunch of PET scans, Positron Emission Tomography. They also looked at MRI. So the PET scans looked at glucose utilisation to see which areas are utilising more glucose than others. It's specific times of the month and the MRI was not a functional MRI. This was just to localise anatomy. MRI is really great for getting a really nice anatomical picture of the brain and they were looking particularly at an area of the brain called the cerebellum, which is the cool little bit at the base and back of your brain that looks like cauliflower.
I mean, that's definitely the best description, right? It's totally cauliflower.
Yeah. And what does the cerebellum do?
So the cerebellum is most well-known for its role in probably balance, I would say. Movement and balance. It's pretty well established for its role there, but it's also kind of growing into a role in anxiety and depression. It has some role in mood. Now, there are many, many areas of the brain that have roles in mood. So, I don't know how far the research has gone since then. I can't really say since 2011, how far this has gone.
But they were interested to see if there was… well, it's tough to say if they did the scan and then said, "Ah, the cerebellum is implicated in mood" or if they said, "I wonder if the cerebellum is implicated in mood and then did the scan, because no one writes the paper saying, "Oh, yeah. We just went on a fishing expedition."
You never do that, but they did find that women with premenstrual dysphoric disorder showed an increase in the amount of glucose they used in the cerebellum during the luteal phase. The luteal phase is when you get the symptoms. It's the back half of the menstrual cycle. And they showed an increase in glucose utilisation in the cerebellum while women who did not experience PMDD did not show that increase, which suggests that there could be a role for the cerebellum in PMDD, in theory.
And so what's your take on what they found?
Well, it was only 12 women in the groups, which isn't a lot. For an fMRI study, well, not fMRI. Sorry, this is a PET study. For a human PET study, that's not really terrible. It's hard to get a lot of people in those studies. They're very, very expensive. I think my main issue with this study was actually the way that it ended up getting covered because what they saw was a change in glucose utilisation in the cerebellum.
What ended up getting written about in coverage of the study was GABA receptors, and serotonin 1A receptors and anxiety. And none of those things were measured in the setting at all. None of them were measured. There are GABA A receptors in the cerebellum. There are serotonin 1A receptors in the cerebellum. Anxiety is a symptom of premenstrual dysphoric disorder. None of these things were measured. They didn't even measure anxiety. They just measured I think negative affect specifically. So they could be roles, but I felt that the coverage of the study emphasised a lot of things that the data didn't necessarily indicate.
Yeah. And on my side of things in the hormone side, 12 is a really small number. And that's not necessarily terrible, like a sample size of 12. It's not insurmountable if you do frequent sampling, so you can actually understand the entirety of the menstrual cycle. But if I remember correctly, these guys did incredibly infrequent sampling, which means they don't really have high reliability that what they think they're measuring is what they're actually measuring. And they also didn't even find any significant differences, if I remember correctly, at least in terms of the stats, in terms of the PMDD versus control folks.
So, it was on my end, what I remember being kind of upset by and what appears in my post is I actually showed some of my raw data of the menstrual cycle and how it looks when you actually look at all the individuals and then how it looks when you average it. And when you average a whole bunch of individuals, yes, it eventually looks like the hormones that you see in a medical textbook. But when you look at them all individually, you can see the average doesn't actually tell us a whole lot about how normal menstrual cycles look. It tells us about what happens when you average them all together. There's not necessarily anything biologically meaningful in that interpretation of hormones.
And so it's just sort of another strike against this idea that like, "Oh, if we just measure this one day in what we expect to be the mid-luteal phase that we're going to get something that's comparable across 12 different individuals and it's just not because everybody's follicular and luteal phases are different lengths and then their quantities of hormones in terms of when they peak or not are going to be really different. So, for me, the frustration was definitely in the quantity of the sampling.
Yeah, I really liked that you showed the raw data and then showed the average. I think, often, we see a lot of averages, especially in the news these days. Polling as an example.
But, we're very-
Oh, don't make me cry.
We're very obsessed with data. I mean, there's a whole field about data journalism. And I mean, we're very obsessed with looking at the data, getting more data and making sense of the data. And often we end up doing that with averages and kind of seeing where averages are and if there's differences between averages. Averages are averages. They're not reality.
And I think it's very easy to forget that for every average, there's someone at one end and there's someone at the other.
Well, and that's why I appreciated how gently you pointed out that the things they measured were not the things that they talked about. Because that's also, in terms of understanding complexity and understanding biological meaning, you should probably measure the things that you think are actually important or if you figure out by measuring one thing that you probably should have measured the next thing, maybe don't give the next thing credit until you do the next study.
Excerpt: Scicurious, also known as Dr. Bethany Brookshire, chats with Kate about PMS and PMDD.
Summary: GUYS SCI IS HERE. Scicurious, also known as Dr. Bethany Brookshire, has a PhD in Physiology and Pharmacology from the Wake Forest University School of Medicine. She is now a writer at Science News, and the science education writer with Science News for Students and Society for Science and the Public. Dr. Brookshire is also a blogger, which is how we met years ago, and a podcaster and host with Science for the People. Dr. Brookshire was the first person I turned to when I wanted to start my own podcast, and her advice has been crucial to me at several points this year. You can attribute many of the good things of this podcast to her, and none of the bad.
In this episode, Sci and I talk about premenstrual syndrome and premenstrual dysphoric syndrome. Both of us have written extensively on the topic, but we focus in particular on two times in the last few years we were compelled to tag team a particular article. Here are the posts so you can follow along:
Tag-team number one on brain activity and PMDD:
- Scicurious (blog): The cerebellum and premenstrual dysphoric disorder
- Me (old blog, archived here): Tag-teaming research blogging: Me and Sci do it up, PMDD-style
Tag-team number two on women feeling premenstrual “hostility” towards infertile partners:
- Scicurious (Science News article): Hypothesis on PMS evolution attracts hostility
- Me (The Daily Beast article): Junk Science: PMS will ruin your marriage
And… here’s one more piece on the concept of PMS as a culturally-bound syndrome, from me: Feedback Loops: the Biology and Culture of Premenstrual Experience.
Subscribe to PERIOD so you don’t miss an episode! Subscribing, especially on iTunes, helps us a ton with promoting the podcast and getting the word out to more people. So does leaving a review, so please do that too!
Do you want to be a patron, or is there someone on your shopping list who would want to be? Check out my new Patreon page for ways to support this podcast. Help me make beautiful things!
Finally, you can also find information about the podcast at Period Podcast on Facebook.
Want a better PERIOD?
Call or write me! I am collecting two things right now: your period questions, and first period stories. Leave me a voicemail with either or both at 262-PERIOD-2 (262-737-4632). Don’t forget to tell me how to contact you if you don’t mind my following up.
Other ways to contact me:
I can’t wait to hear what you think! Thanks for listening!
Direct download: here