E217: When babies inherit trauma-affected gut microbiomes from Moms

A diversity of bacteria and microorganisms making up the gut microbiome supports both our physical and our mental health. Research has shown that stress and trauma can negatively impact the microbiome. But a recent study took that finding to a new level. This was a study published in the Proceedings of the National Academy of Sciences. Scientists now see inflammation-related microbiomes in babies born to women who experienced mistreatment or adversity during their own childhood. These microbiomes predispose children to physical and mental health problems. We'll talk today with the co-author of that paper, Fran Querdasi, from the University of California, Los Angeles. Interview hosted by Kelly Brownell.

Interview Summary

This topic is so important, and you just hear time and time again from experts all around the world how profoundly the microbiome was influencing our health and how many factors affect the microbiome. But now to think about this generational matter that you addressed in your research is interesting and scary, in a way. Let's first start off with this question about how you studied these mothers and the children. What were you looking for?

The goal of the study was to see how experiences of adversity or hardship across two generations might be related to the composition of the children's gut microbiome, or in other words, which microbes were living in their guts. So, for this paper, I worked with colleagues at the University of California-Los Angeles, as well as a team of scientists in Singapore who are currently conducting a big birth cohort study called Growing Up in Singapore Towards healthy Outcomes, or GUSTO for short. That study has thousands of mothers and families enrolled but, in this paper, we focused on around 450 families who had data on what we were interested in - the mother generation, as well as her child generation. We specifically wanted to study the children when they were around two years old because the gut microbiome develops really rapidly during that period from birth until around two years of age. 

In this study, we asked mothers to tell us about three different kinds of adversity. First, their history of maltreatment. That would be things like abuse and neglect in their own childhood and then kind of moving forward in time, any symptoms of anxiety during their pregnancies. Then moving forward again into the children's generation, their children's exposure to stressful life events. So, things like their parents' divorce or the death of a family member from birth till two years of age. At two years of age, we collected poop samples to analyze the children's microbiomes. Then we also asked families to report on their children's social emotional problems. So, things like aggression, sadness, issues with attention on when they were two years old and then again at age four because we really wanted to see also how their microbiomes were related to their early childhood health.

I'm eager to hear what you found but first, let me say I'm impressed that you even bothered to ask this question because one wouldn't think that traumatic experiences decades ago in the life of a mother would affect the microbiome of a child today. So, tell us, please, what did you find?

We found that each of the adversity experiences that we asked about - so abuse or neglect that the mother experienced in her own childhood, the mothers' symptoms of anxiety during pregnancy, as well as children's experiences of stressful events in their early life - all of those seem to have an impact on the children's gut microbiomes. Specifically, we found something interesting, which was that some of the microbes that seem to be related to adversity we think that they might perform similar functions to those that we found were related to the children's social emotional health, both at two years and then at four years of age. We think that those microbes probably play a role in regulating the immune system and inflammation. Our findings kind of hint that maybe disruption to some immune-related functions within the gut could help explain how some children go on to develop mental health struggles after they experience adversity. And how that intergenerational experience of adversity shows up in subsequent generations.

Like I said, it's hard to imagine that things so distinct in timing can have such a big impact. How is it possible that adversity experienced by a mom in her own childhood could affect her child now in terms of the microbiome?

That is pretty surprising. You think that it's so far in the past, but it's really striking that it does still appear to have an impact. This study was the first one to find evidence for that in humans. There have been studies in animal models, researchers that work with rats and mice, and there was evidence the mom's experiences during childhood affect their children's gut microbiome. There is other research that studies this phenomenon, called intergenerational transmission of adversity, and that's when