Susana Carmona, neuroscientist: “We know more about the Universe than about the female brain” | Health and wellness

Motherhood is a life-changing event for women, but it also affects—perhaps permanently—their brains. Susana Carmona (Terrassa, 43 years old) knows this very well because, together with her team at the Gregorio Marañon University Hospital (HGUGM), eight years ago she signed the first study on the neuroplasticity of this organ during pregnancy. They found, among other things, that pregnant women’s gray matter shrinks in the months before and after childbirth, although the causes and purposes of these changes remain a mystery that needs to be studied in depth. “The more we move forward, the more we know about the female brain, but more and more questions arise,” admits the doctor of neurobiology who leads the Group Neuroimaging HGUGM and has just published a new study on this issue.

TO. Why does the brain of pregnant women change?

R. The question is, how can the brain not change? During pregnancy, a woman’s entire body changes. Your cardiovascular system, your kidney system, your legs will grow, your skin color will change… This happens because all organs have to adapt to pregnancy. The difference is that in some cases we directly know a particular function, why it adapts, and in others we do not. But what I find strange is that no one asked what happens in the brain when a woman’s whole body changes.

TO. Why do you think no one asked this question?

R. There is a gender bias in biomedicine, which is very important not only when we talk about pregnancy. Menopause is also another great unknown effect of hormonal treatment. Today, many girls are taking birth control, and there is still not enough research to know what is happening at the brain level. We know more about the universe than we do about the female brain.

TO. What exactly did they find in this first study?

R. The first thing that was discovered, and the reason why it had such an impact, is that during pregnancy a woman’s brain changes a lot. And when I say deeply, I mean that I have been researching various mental pathologies and analyzing the brain for many years, and I have never seen changes as powerful, as noticeable and consistent as those that occur during pregnancy and motherhood. We saw that a woman’s brain changes, and the more it changes, the better the connection with the child. This raises many questions that we are now exploring.

TO. For example?

R. People want to know what happens to fathers if they, too, change like mothers. Or these changes are similar to those that occur during adolescence. Since then, we have not stopped researching to answer all these questions. In 2019, we published another study that compared the anatomical changes that occur in a woman’s brain during pregnancy with those that occur in girls during puberty, and confirmed that at the level of shape and size, these changes are very similar. . In both processes, a decrease in gray matter is observed.

TO. He said it like it was something bad…

R. Now, when you say that a woman’s brain is decreasing in volume, everyone automatically thinks about degeneration, about atrophy. But in biology, less is not always worse. To study these changes, we use magnetic resonance imaging, which allows us to find out what is happening at the level of the brain. To date, we have not observed an association with cognitive changes in the way tasks are performed during and after pregnancy. If we look at animal models where more research is being done in mice, we see that neurons in some regions are more connected and in others less so.

TO. What exactly does this mean?

R. Right now we are not entirely sure of our hypothesis. At first, because we saw changes similar to adolescence, we thought it was due to a mechanism similar to synaptic pruning (the process by which most of the unnecessary connections formed in the early years of life are eliminated). Now everything is not so clear to us, because the changes are very dynamic. We see that some changes are saved and others are not. This tells us that the cells behind these changes must be very dynamic. And we know that during pregnancy, the mother’s entire immune system must be compromised in order to tolerate a creature that is genetically different from you. This could be an explanation, but we are now exploring this hypothesis.

TO. Is it possible that the change has the function of preparing women for care?

R. This is what we want to discover, but to say this now would be philosophizing. There will be a study published soon that we are working on with the team at the Autonomous University of Barcelona, ​​which may give us some clues, but I can’t give too much information yet. I can say that this is not a direct connection. It is not the brain that switches to caring, which is often misinterpreted in the results. It was the way it changed that made you care, and the fact that you care is what allowed this species to survive as it is.

TO. In the latest published study, they found differences depending on the type of birth.

R. This study was not specifically designed to examine birth type, but provided us with useful information in this regard. We had 12 women with elective cesarean sections, 11 with emergency cesarean sections, and approximately 80 with vaginal births. Comparisons are still preliminary to provide definitive answers, but after comparing birth types, we saw that there was no difference between an emergency C-section and a vaginal birth. The difference between a planned caesarean section and the rest. Because the hormonal environment that exists during labor, when contractions begin, has nothing to do with what happens during pregnancy or the postpartum period. This is a unique situation that, if left unchecked, as in the case of women who have had a planned Caesarean section, leads to other changes in the brain.

TO. Better or worse?

R. It is too early to talk about this, and it is very dangerous, since it is not yet ready for use in clinical practice. This is what we discovered in this study and what we will have to deepen by controlling for all possible variables. We have hypotheses as to why this happens, for example that childbirth itself already causes certain neuropathic effects.

TO. One thing we know for sure: the more the brain changes, the stronger the bond between mother and child. How is it measured?

R. It is very difficult. The only way we have is to do neuroimaging studies and fill out questionnaires. These are questions that assess whether the mother develops hostility towards the child, what pleasure they experience when interacting with him… Scales that are tested and will give you a score. In the first study, we saw that changes in the brain predicted attachment after birth. I do not believe that this connection is direct, it must be mediated by other factors, and it is not absolute. It’s not that if my brain doesn’t change during pregnancy, I won’t have a connection with my baby. So how do we move from brain, anatomy, brain to connection? Well, all these questions about whether there are hormonal factors that mediate them, immune factors, inflammatory factors, wellness, depression, anxiety, all of that is something we have to work through.

TO. Can we talk about maternal instinct in neuroscience?

R. It is very difficult for scientists to name things. When you start looking for definitions of instinct in every possible dictionary, you will discover subtleties that can make the answer “yes” or “no”. For me it is yes. You can talk about maternal instinct, but with my mental definition of what maternal instinct is, which is not the desire to be a mother or the fact that you suddenly give birth and know what to do with the baby. For me, maternal instinct is the motivation to be in contact with the baby. Not even enjoying communication with him, but experiencing and contacting him to find out what is happening. Moreover, if this instinct did not exist, we would become extinct. Without the motivation of care, which screams and often worries, man as such would no longer exist.

TO. How long do these changes in women’s brains last?

R. We don’t know, but we have evidence from other studies that they may persist throughout life. We looked at what happens six years after giving birth, and changes are still being seen. But there are other researchers who take large databases of tens of thousands of participants and compare those who became mothers with those who did not. There are already 70-year-old women who continue to experience specific changes. It is also impossible to say for sure whether biology is behind these changes or whether they are also influenced by the environment. This may depend on the type of upbringing or lifestyle. There is also research that links them to the hormonal levels of estrogen that women are exposed to during the nine months of pregnancy, and that in the long term this can affect how a woman experiences menopause and how she transitions into adulthood.

TO. What happens in subsequent pregnancies?

R. This is what we are currently investigating, along with possible changes in the parents’ brains. But to draw conclusions, you need a lot of data, this is work that takes time.

TO. Is it difficult to find participants?

R. This is very difficult, especially depending on the research approach. We need to monitor women before they become pregnant and then in the early postpartum period. You’ll have to do a lot of MRIs, but not all of them will be helpful since many women who start the study won’t get pregnant. Others may lose the child or simply become uninterested in the child because this observation lasts for many months. In addition, from an economic point of view it is very expensive, researchers must be very motivated to invest their time in projects that take much longer than science in Spain allows.

TO. Apart from researching a topic about which very little is known, what is this knowledge used for?

R. A few things. If we transfer this to the clinical area, the first thing that comes to everyone’s mind is postpartum mental pathology. Today we are trying to predict, treat and treat postpartum mental pathologies and do not even know exactly what happens in a woman’s brain during pregnancy. Thus, one of the most direct applications would be to try to develop treatments that target perinatal pathologies. It is also important to understand how this may affect menopause or how it may affect women who are at higher risk of developing Alzheimer’s disease.

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