Early Life Stress, the Microbiome and Children’s Behavior

Well, this will come as a complete shock to most of you.  (NOT)  The bacterial contents of children’s guts affects their behavior.

One of the big biome stories of the last few days is that research out of Oregon State University and the University of Oregon has shown that school-age children with behavioral issues have different bacteria in their guts than the normally behaved controls.[i]  Of course, this does not prove that the gut bacteria are determining behavior.  It may well turn out that the opposite is true:  behavior determines the gut bacteria.  What these scientists actually did was zero in on children who faced “…a range of adverse experiences and caregiver stressors and relationships…” to see if they had alterations to the microbiome.  Their “…results indicated that the taxonomic and functional composition of the gut microbiome correlates with behavior during a critical period of child development.”

That is, “caregiving behaviors” modified the gut microbiome.

Now, as the mother of a child with autism, let me say that, like the rest of you in my shoes, I tend to be pretty hypersensitive about anything that smacks of “refrigerator mother” syndrome.  In this case though, please remember that these researchers do state that this proves nothing more than a correlation, not a causation.  This research is not a blame game.  It is a study of how stress of any kind alters the gut biome which, in turn, may alter a child’s behavior.  And this is really important to know.

To summarize, the scientists stat that “While we cannot infer causality within this study, these findings suggest that caregivers may moderate the gut microbiome’s link to environment and behaviors beyond the first few years of life.”

So let’s all take a deep breath and talk about the science.

1.   “Ongoing research seeks to characterize the underlying mechanisms by which adverse environments and caregiving behaviors (both positive and negative) influence a child’s behavioral development. Such research demonstrates that these environments and caregiving behaviors can alter the developmental trajectory of central, autonomic, and peripheral nervous systems function.”  Well, that makes perfect sense, right?  Stress in a family would of course tend to lead to stress in a child.
2. We all know that stress has profound physiological effects. We all know, too, that stress – both physiological and emotional – impacts the microbiome.  I’ve written about this before, for example, here and here.
3. We Biome Buzzers are pretty comfortable with the idea that our gut bugs influence our behavior, and vice versa. Here are a couple of posts on that topic:  here and here.

So following that trail of logic, it makes perfect sense that caregiving behaviors influence a child’s microbiome which, in turn, may influence a child’s behavior.

In this study, the researchers looked at 40 children 5 to 7 years of age.  Their parents filled out questionnaires that asked about socioeconomic risk, behavioral dysregulation, caregiver behavior, demography and gut history (like antibiotic use).  The parents were also asked to journal the child’s diet for 1 week.  Fecal samples were then collected from the children.

A quick summary of their findings:  “…our study reveals supportive evidence that the psychosocial environment continues to shape not only the taxonomic composition, but also the functional potential of the microbiome…”

It turns out that economic and social forms of adversity lead to different microbial profiles.  For example, poor economic status may lead to greater toxic exposures, which alters the microbiome and intestinal permeability.  This, of course, leads to alterations in the immune system.  The quality of the child-parent relationship were indicative of altered functionality of the gut microbiome, and subsequent depression and impulsivity issues in the children.  (By functionality, they mean how the microbiome performs.  For example, are vitamins produced normally?  How are amino acids synthesized into neurotransmitters, etc.)?

The authors conclude:  “…we discovered that not only are there significant associations between metrics of socioeconomic risk and behavioral dysregulation with the microbiome, but that the quality of the parent-child relationship (here parentally reported) and parental stress statistically moderated these relationships.”

I don’t think there’s anything revolutionary here, but still, it is an interesting little paper.  It’s yet another confirmation of the critical importance of the gut-brain axis,  and the fact that external factors ranging from diet to lifestyle affect that biome and ultimately, human behavior. The lead researchers, Thomas Sharpton, believes that “… if large studies confirm these findings, it might be possible to figure out a way to use microbiome information to predict how a child’s behavior might develop. Having that information might lead to earlier — and possibly more successful — interventions.”[ii]   And everyone likes interventions!

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[i] Flannery, JE, Stagaman, K, Burns, AR, Hickey, RJ, Roos, LE, Glultiano, RJ, Fisher, PA, Sharpton, TJ. Gut feelings being in childhood: the gut metagenome correlates with early environment, caregiving, and behavior.  mBio. 2020; 11(1).   doi: 10.1128/mBio.02780-19

[ii] https://www.webmd.com/children/news/20200121/could-a-kids-microbiome-alter-their-behavior#1