Women's Brain Business |
Lynne Malcolm: Baby brain, pre-menstrual syndrome, menopausal brain fog; what's going on in women's brains?
Sarah McKay: There seems to be an assumption that all women have a female brain and all men have a male brain and we can sort ourselves into a pink bucket and a blue bucket by virtue of our brain structure and our brain function.
Lynne Malcolm: But it's not that simple.
Hello, I'm Lynne Malcolm with All in the Mind on RN, and some women's brain business.
Neuroscientist Dr Sarah McKay has studied how our brains are shaped and changed by our lives, genes, hormones and society. She became particularly interested in women's brains when she was writing an article about so called 'brain fog' reported by some women during menopause. It led her to write The Women's Brain book: The Neuroscience of Health, Hormones and Happiness. In reviewing the neuroscience literature on women's brains she found some aspects which were very well researched, but there were some huge gaps too.
Sarah McKay: For example, I went in to dig into the research to look at what happens to our brain when we are taking the oral contraceptive pill, and there was a review written a couple of years ago with the title '50 Years of the Contraceptive Pill: Time to find out what it does to the brain'. So there were some real surprising gaps in our knowledge as well.
Lynne Malcolm: Why do you think that is?
Sarah McKay: Look, I think there's so many reasons. Neuroscience is incredibly broad and deep and complex and we've barely scratched the surface of the cortex. There's just so many questions that remain unanswered, not because someone has not thought of them, there's just such a breadth and a rich field of research out there just still to be tapped into.
Lynne Malcolm: Women aren't included in trials as often as men are.
Sarah McKay: Yes, that is one of the reasons why, and that was something that surprised me when I first started delving into the literature. Yes, there are lots of longitudinal studies that have been designed to look at the lifespan of women, but when we look to some of the research such as clinical trials, we know that the majority of them have traditionally been done in young, healthy, fit males, and there's a number of reasons for that. Some of that is just tradition, we just carry on doing the same research and using the same subjects that we've always done because it's just easier that way. Sometimes women have been excluded perhaps. If a woman fell pregnant during a drug trial it could…for obvious reasons it could be incredibly damaging to her health and to the health of the baby. So women have been excluded for those reasons.
There is also some really interesting reasons that women have been excluded from some of the neuroscience research. Researchers are just kind of too scared to start looking at women's health and comparing it to men's health for fear of having their research abused to support outdated gender stereotypes, so they've kind of shied away from that. And then there's also some of the more logical reasons. Perhaps we may be looking at endocrinology, so it may be more confusing to the dataset to include women in there because of our fluctuating hormones across the month, those types of reasons. There are numerous reasons why.
Lynne Malcolm: There are some widely held assumptions and stereotypes about male and female brains. For example, women are more emotional, men more analytical, women are better at multitasking, and the list goes on.
Sarah McKay: Yes, I think the main idea out there, and I've been asked this so many times while I was writing the book, is are male and female brains different, are they wired differently? And there seems to be an assumption that all women have a female brain and all men have a male brain and we can sort ourselves into a pink bucket and a blue bucket by virtue of our brain structure and our brain function. But it's virtually impossible to do that. We could never look at a brain scan and say, well, that's a male brain, and look at another brain scan and say, well, that's a female brain, and neatly sort ourselves like that.
The way the research seems to be tending towards the moment is this concept of mosaic brains whereby we each have our own particular individual brain, but it is made up perhaps with some structures or functions which may tend towards more female-like and other parts that are more male-like. And I use an analogy in the book whereby our brain is like a mosaic made up of lots of little…some pink, some blue, mostly shades of purple, indigo and violet. So if we were to look at it from a distance it's a mosaic, and we can't neatly split them into pinks and blues in the same way that we can divide ourselves up perhaps by our genital anatomy.
Lynne Malcolm: But are there some areas that are valid, some of the stereotypes are quite valid? For example, men's ability with space, with spatial recognition.
Sarah McKay: Yes, that is one of the biggest average differences we see, and if we want to delve into our male and female brains, definitely we need to typically start looking at populations of people, and what we started digging into is how different are these differences? Because what we tend to find is there are average differences within a population, so how different are those differences? And one of the biggest differences is in this peculiar ability to rotate a 3-D object in your mind's eye. So men on average tend to be better at that than women. Of course there are some women who are brilliant at that and some men who aren't very good at it at all.
Now, what's the origin of that difference? That's really kind of a more interesting question. Is it that a male brain is wired to be able to rotate 3-D objects from conception or are they shaped that away in the womb? Or is that something that perhaps young boys learn to do more so than young girls? It's very hard to untangle that influence of biological sex and experiences of gender into something like the ability to rotate a 3-D object in your mind.
Lynne Malcolm: So your book outlines what happens in the brain through all life stages. Why is it so important for women and men to understand how the brain works through different stages?
Sarah McKay: One of the researchers that I spoke to, Sarah Romans, who is a psychiatrist in New Zealand and she runs a clinical practice and also does research in the University of Otago, she said something really interesting, that our health is very much influenced by our expectations and our understanding, and a lot of her research supports that notion, that what we almost expect to happen, we may have a bias towards experiencing that in its own way.
We know from the research that there are so many interacting factors that influence our brain and our nervous system health. So we have what I call our bottom-up biology, everything from our hormones to the amount of sleep we get and exercise we have. There's the outside-in experience, life experiences we have, perhaps stressful events. And also those top-down thoughts and mindsets and expectations, and all of these can interact to influence our experience of health. So if we understand that and we can take a more perhaps sceptical and nuanced approach to health by having an understanding, by being educated on that, that can influence our health outcomes.
Lynne Malcolm: In The Women's Brain Book, Sarah McKay helps us understand how the female brain changes as we move through our life stages. She emphasises that the first 1,000 days of a baby's life, beginning at conception, is crucial in determining the child's health. For example, maternal stress can have a significant effect on the unborn child.
Sarah McKay: If you have ever been pregnant, you would know that it's a time of great concern and worry, and I know I spent a lot of time worrying during my pregnancies, I've got two boys, and my mum and my sister were continually telling me to stop worrying, and that made me…then I started stressing out about the fact I was worrying. So it was interesting to delve into the research around how much stress does a woman have to be under for it to influence her baby. So the research is very clear that typical levels of maternal angst and anxiety are fine, that's not going to influence the baby in any way, and in fact the baby is shielded from its mother's stress hormones by the placenta and by various other metabolic and biochemical barriers that are in place.
However, if a mother is exposed to extreme stress or trauma, such as perhaps experiencing a natural disaster or something like that, we know that it can have impacts to that child's health throughout the life span. So there was a study that was done in Canada, it was probably…I can't remember off the top of my head the year that it happened in the '90s. There was a terrible storm that happened in the winter months in Montréal in Canada, there was an ice storm, the ice collapsed all of the electricity pylons, so the entire town of the city of Montréal had no power. A lot of families had to be evacuated. It was an incredibly stressful time.
Now, no one died, it wasn't up there with something like a tsunami, but it was stressful enough. Researchers went in and then were able to look at the women who were pregnant during the time of this ice storm and in the last 15, 20 years they have been following the children that were born after that disaster, so they were in utero during that time, to look at their health outcomes.
And none of them, to be fair, have had any incredibly serious health outcomes, but there are differences in their cognition, their behaviour and other health outcomes that we can look at compared to children who were not in utero during that stressful time. So I think it's important to recognise that normal levels of maternal stress are okay, but there perhaps is something to that idea that we do need to be taking a little bit of care of women during pregnancy.
Lynne Malcolm: Many women report feeling more forgetful, less attentive and a type of fogginess in the brain when they're pregnant. Sarah McKay investigated what's known as 'baby brain'.
Sarah McKay: Well, certainly the structure of our brains does change considerably when we are pregnant. In fact, beyond childhood development and the refinement that happens in parts of the brain during the teenage years, the biggest structural change that we see in women's brains is during pregnancy, and a very neat study was done at the end of 2016, and was published looking at the brains of I think it was about 25 women. They were scanned with MRI, so they were just looking at brain structure before they fell pregnant, a few months after their first pregnancy, and a couple of years after their first pregnancy.
And as a control, to see whether the structural changes that were seen were due to pregnancy itself rather than the act of parenting, the husbands, or the fathers of those babies brains were also scanned at the same time point. The men's brains didn't change, they were obviously involved in the parenting as well, but there was certain regions of the women's grey matter or their cortex which became thinner during pregnancy.
And this idea of part of the brain shrinking always makes it sound a little bit like it's degenerating, but we know from what happens during the teenage years that often thinning of the cortex is showing refinement of connections and elimination of unneeded connections, and it has almost become streamlined. And it was specifically those regions of the brain that are involved in social cognition and empathy, and the researchers concluded that pregnancy provides a safe place for a baby to grow in utero, it prepares a mother's body for becoming a mother, for motherhood, to be able to breast feed and nurture that baby. But it also prepares a mind, a brain for motherhood, and that's the mothers' brains became…these empathy and social cognition brain regions became fine-tuned to be able to respond to their babies emotionally and to be able to understand and pick up their babies' social cues, which of course is what we need, we need parents to be able to do, to respond to their babies.
Now, baby brain, as we would call it colloquially, is something different, and this is this idea that during pregnancy or motherhood we kind of lose our mind and we are forgetful and we can't pay attention and everything kind of…you become a bit docile and dopey. And surprisingly this is a reasonably well researched area, both in animals and in humans. Interestingly if we are to look at the little small scurrying animals of the lab where neuroscientists like to spend a lot of our time, pregnant females and mothers, we could almost say they become smarter. They show cognitive enhancement, they are far better able to find their way through a maze, for example, remember how to navigate their way through a maze, than their virgin sisters or non-pregnant animals. All of the hormonal and chemical signatures of pregnancy are certainly geared towards the same in women, in humans.
We are exposed to more estrogen during a pregnancy than we are in the rest of our lives in total, and we know that estrogen does enhance cognition, it enhances memory, it enhances reasoning, it enhances all of the measures that we would take, those cognitive measures that we would do in a lab.
What's interesting is when women are brought into the lab and a lot of these studies are done, most research, not all, but a lot of the research will support this idea that women's memory, attention, perhaps their maze finding ability if they were to find their way through a virtual maze is unchanged by pregnancy, occasionally it is even enhanced.
The studies that have found that seem to support a lot of women's experience that they feel like they've become more forgetful more so finds this is the case in the last trimester of pregnancy, and often this is when women are suffering from sleep deprivation. Because if you've gone through a pregnancy you know you've got this big belly and there's a moving baby and those kind of hormones in those late stages of pregnancy kind of keep you up, keep you awake. And so it's more tightly related to lack of sleep than pregnancy itself. And it's certainly similar in those early stages of motherhood, you know, babies keeping you up multiple times a night. You are sleep deprived. It's the dads that are suffering too, they are the ones getting up. They've also got what you might call baby brain, but it's more closely related to lack of sleep and stress than the fact that you've become a mother and that your brain has lost its way.
Lynne Malcolm: You're with All in the Mind on RN, I'm Lynne Malcolm, and today we're delving into women's brain business.
My guest is Dr Sarah McKay, author of The Women's Brain Book: The Neuroscience of Health, Hormones and Happiness.
She says it's important for us to understand how the brain works during different life stages. Menstruation is one of the few phenomena all biological females experience, and it's a cycle defined by fluctuating hormones. Many women feel their moods are more unstable around this time. It's well known as pre-menstrual tension or PMS. Sarah McKay looked at how the ups and downs of the hormones across the menstrual cycle impact women's emotion and their ability to think.
Sarah McKay: Well, the great news is that there is no evidence that the natural menstrual cycle in any way impacts our ability, any of these higher order executive functions, so that's great news for those of us who are out there holding down jobs et cetera, great news. The evidence on whether our menstrual cycle affects us emotionally is more mixed. So if you look at the very, very granular studies of measures of emotion in the lab, perhaps measures of emotional recall, there does appear in some women to be a bit of a variation over the monthly cycle.
So that high progesterone phase in that week or so after ovulation before your period, there does appear to be a slight tendency for emotional memories to become more firmly embedded. So if you were perhaps to experience some type of trauma during that particular phase of the month, there is more of a slight tendency that you would be more likely to develop perhaps some type of post-traumatic stress symptoms or that that traumatic memory or highly emotional memory may become more firmly embedded. But these are very granular studies of emotion. So I then thought I'll go and take a look as what's a far more commonly experienced emotional event through the course of the month, so I thought I'll go and look at the research on PMS, and that research was really surprising.
Lynne Malcolm: What was that?
Sarah McKay: Well, I thought it will be very well researched and there will be plenty of stats and data in there looking at how many women suffer emotional turmoil in the week before their periods, and there was no data anywhere that matched any other data. One paper I found compared rates of PMS reported in different countries. In France, for example, it was hovering around 15%. In Iran it was around 95%. So all I could say was somewhere between hardly anyone and almost everyone suffers symptoms of PMS. And the symptoms reported kind of encompasses almost any physical emotional symptoms that you can imagine.
So again, I went back to the research that came out of New Zealand from Sarah Romans, and she was very highly sceptical that all women are suffering emotional turmoil in that week before their periods, and certainly thought there were far more women blaming their hormones for their moods than were really experiencing any true symptoms. So she designed a very clever study called the Mood and Daily Life Study whereby women were prompted by an app on their phone every day to record their mood and they were given the options of positive and negative valence, so they weren't just being asked 'are you sad and tired and grumpy and weepy', they were also asked if they were feeling happy and upbeat and energetic. They were asked to record what sort of stress levels they were feeling, how emotionally supported they felt, what were their relationships like, what was their physical health like, and also the day of their cycle. So these were all naturally cycling women, none of them were on the pill.
Tellingly, they were not told that the study was about PMS. And what she found was only one in 20 women in that study showed any true negative emotions in that week before their period. So it was only about one in 20 women were suffering what we would call PMS or PMT, premenstrual tension is the other word. Which was quite surprising to me because I thought, well, everyone seems to claim they have it. I've personally never really felt like I suffered from it, I thought I was missing out. But certainly one in 20 women was what she found.
So I said what do you say to the other 19? Are we dismissing, the symptoms are all in their head or it's all in their mind? How do you then approach discussing these findings with women because some people might find that quite dismissive or they are being told you're imagining it. And she just says she tries to encourage…well, first of all she says let's get some data on that first, and she tries to encourage women to take a more sceptical and nuanced approach to their health because what that study found was that women's mood was far more likely to be influenced by how stressed they felt, their physical health or how much social support they had, far less so than their hormonal status.
Lynne Malcolm: And so to menopause. We have a similar perception that things start going awry for women because of the hormonal changes at this time
Sarah McKay: Certainly the literature shows or the literature finds that that is one point in life when hormones, instead of being a backseat driver or just one voice in the crowd, their influence does come to the fore. Typically it's in the perimenopause, the years leading up to the menopause, which is the women's final period. And it's a bit of a hormonal rollercoaster for some women, not for all women. So about a quarter of women may suffer reasonably severe symptoms, about half of women may have the odd symptom and another quarter of women may just sail through completely unaffected. And the symptoms are caused by the rollercoastering of hormones as the fits and starts of the ovaries as they are kind of winding down their duties, and that ovarian–brain conversation that has been going on starts to disconnect.
What was interesting is it's very hard…it's kind of a chicken and egg scenario, it's very clear that hormones cause hot flashes in some women or hot flushes, and hot flushes can then cause women to wake up at night, which can cause ongoing sleep disturbances, which can then perhaps trigger insomnia, which can perhaps trigger mood disorders. So what is the chicken and egg scenario here, and it's very, very hard to tease that out.
What we do know in women who choose to take hormone replacement therapy or HRT is it does help with the hot flashes. It doesn't always help with all of the other symptoms. I spoke to another researcher who said perhaps if a woman has waited a while to start seeking treatment, perhaps her hot flashes have caused insomnia, the insomnia has become set in and taking hormones isn't going to help that. So again, there is often a lot of things going on. Again, it's not solely hormones that are the driving factor here, physical health and well-being, how well you're taking care of your diet and your exercise and how much sleep you are getting, what are your social support systems like, what other external stressful events are happening, all of these combine for every woman's individual experience of menopause.
Lynne Malcolm: And so what about brain fog which refers to something that happens during menopause or in the ageing brain?
Sarah McKay: Yes, and that's more of a colloquial term and I've actually heard it debated amongst researchers and doctors about whether it is real or not, and I think that's a bit of an unfortunate argument because it's not not real. I mean a woman may turn up to a GP and say, 'I feel like I am suffering from a little mild cognitive decline,' which may be the correct medical terminology, but certainly it's a real experience. It's not imaginary, a lot of women do experience that, and men too at various points in life, and it can be due to a whole host of reasons. Often it's due to disrupted sleep and particularly if there is a lot of stress going on in people's lives, they are distracted, they can feel vague and foggy. It's very important to realise that a lot of women experience this when they go through menopause, a lot of women then recover from experiences of brain fog once their hormones…the rollercoaster has finished and they tramline, or if they perhaps choose to take HRT or some other type of hormone replacement therapy. And it's not necessarily the first sign of Alzheimer's disease or dementia.
Lynne Malcolm: So in the ageing brain, is there a difference between the way that a woman's brain ages and a man's brain ages?
Sarah McKay: I didn't really find too much in the literature around that. There's certainly differences in terms of how many…you know, if we were to look at all the diagnoses of Alzheimer's disease, for example, we would definitely see more women being diagnosed with Alzheimer's. We know the greatest risk factor for developing Alzheimer's disease is getting older. Women tend to outlive men, and so there's more older women alive to develop these ageing diseases of the brain.
In terms of the typical ageing process, there's quite an interesting finding whereby men don't live on average as long as women, but they tend to live reasonably healthy lives and they always drop off the twig quite quickly when they go, whereas women tend to have a bit of a slower decline, they live longer but they don't necessarily in those extra years live healthier, and that's probably reflected also…that's their typical health profile but we might also see those same changes taking place in their brain.
Lynne Malcolm: Jeanne Louise Calment was a French supercentenarian who passed away in 1997 at the amazing age of 122. Sarah McKay was keen to find out more about her and why she lived so long.
Sarah McKay: I think everyone wants to know her secrets. Well, she smoked until she was about 117 or something, so I'm not sure whether that's the secret we all want to undercover. You don't know how much of these are just stories, but apparently she only gave up because she was too proud to ask the nurses in the nursing home to light her cigarettes.
She certainly had good genes because she had a brother who lived to 95, so she had that good healthy genetic baseline in there. She also lived in a second storey building until she was…I think until she was moved into a nursing home after the age of 100. So she was walking up and down stairs every day of her life. She rode a bike.
She had an incredibly rich and active and engaged lifestyle through her youth, which was quite unusual for a woman of her time. She played a whole host of different types of sports and went to the opera and went to the cinema and was reasonably well travelled. So she certainly had very rich experiences through her lifespan.
One of the most fascinating pieces of…the most interesting and intriguing story that I found when I was researching this book was some researchers went in to have a look at…do a kind of a profile on her when she was 118, and they did a series of brain scans to take a look and see what does a 118-year-old brain look like. They said her brain looked on average more like that of an 80-year-old. So her brain was certainly reasonably resilient.
But what was so cool was they went in and they did a whole host of neuropsychological tests on her over the course of six months, they went in and did multiple periods of testing with her. So she had been at this time just sitting around in a nursing home by herself and she said she waits for death and for journalists, so there was not a lot going on in her life. But what was so fascinating to me was over the course of the six months was that her test scores improved. The reason for that must have been that that continual social and intellectual engagement and the continued testing process itself. So her maths scores went up, her tests of verbal memory and reasoning went up over the course of that, even at the age of 118 her brain retained that capacity to learn and be changed by experience. So it retained its capacity for what we would call neuroplasticity, even at age 118.
Lynne Malcolm: That's encouraging.
Sarah McKay: It is.
Lynne Malcolm: So overall, what are the most important take-away messages that you've drawn from the research on women's brains?
Sarah McKay: Well, I guess I rather naïvely went in to writing the book as a neurobiologist thinking it would be very much a book about biology, how do our hormones influence our brain, and I very quickly realised that at every life stage…you know, we could look at puberty, that the emotional and cognitive and social changes a girl goes through aren't solely driven by her hormones. There's a lot going on in a young girl's life. And at every of these major life transitions that we go through, I thought it would be…hormones would be kind of the queen maker, they would be the loudest voice, and they are just one voice in the crowd.
I've spent my neuroscience research career looking at that…not the nature/nurture debate because it is not really that anymore, but I was very aware of how important experiences are in shaping our brains and the research kind of reminded me of that again, that our brains and nervous systems evolved to be influenced not only by our hormones, they are not the only voices in the crowd as women. Our social context is so important, our life experiences, what's going on in the world around us is just as important, our thoughts and our feelings, our mindset, our expectations are also important. So for me that was that tap on the shoulder, that reminder, and I hope that people take that away from the book too.
Lynne Malcolm: Dr Sarah McKay, author of The Women's Brain Book: The Neuroscience of Health, Hormones and Happiness. Thanks to the team, producer Diane Dean, sound engineers Que Nguyen and Judy Rapley. I'm Lynne Malcolm, thanks for joining me, until next time.
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