Can the gut microbiota predict behavior in mentally healthy individuals?

Yangwenshan Ou
About the Author

Yangwenshan Ou conducts her PhD research in the Molecular Ecology group at Microbiology Laboratory, Wageningen University and Research (WUR), The Netherlands. She specializes in the development of gut microbiota from birth to puberty and the link between behavior and gut microbial compositions in children.

Maintaining mental health is important. The gut microbiota, mainly composed of bacteria, is considered to play a pivotal role in retaining mental health. It is not surprising that most gut microbiota-brain related studies are focused on diagnosed mental disorders,[2] due to their severity and urgency. With a better understanding of the role the gut microbiota plays in mental disorders, researchers start their explorations in a wider group, that does not have a disorder. This group is often called the “neurotypical population”.

The neurotypical population is defined as medically and psychologically healthy individuals who have a normal pattern of neurodevelopment.[1] Though these people are not clinically diagnosed with neurodevelopmental issues, they may have different levels of mental problems below the clinical cut-off. Knowing how the gut microbiota is related to behavior in mentally healthy people may help to develop early interventions to prevent future severe mental problems and illnesses.

In the past three years, I have been diving into the relations between the gut microbiota and child problem behavior in healthy cohorts (i.e. the neurotypical population). Problem behavior consists of internalizing and externalizing behavior. Internalizing behavior includes symptoms of anxiety, depression and social withdrawal, while externalizing behavior has disruptive, hyperactive and aggressive traits. Children with more internalizing problems may have a larger chance to suffer from depression later in life.[3] Increased externalizing behavior is related with worsened family relationships and more economic problems in adulthood.[4]

From studies in our lab, we found some connections between specific gut bacteria and problem behavior. However, due to a great lack of similar studies, it is extremely difficult to validate these interesting findings. For example,  since both the gut microbiota and problem behavior can be affected by some covariates (e.g. diet and age), it is also important to correct for such differences in our research. Additionally, selected covariates may differ largely between studies, and this makes the comparison even more challenging. This makes it very difficult to draw firm conclusions from our research, at this point.

Back to the question posed in our Title: from a research perspective, there is not yet a clear answer on whether gut microbiota can predict behavior. Fortunately, as an increased number of studies begin to focus on the mentally healthy (“neurotypical”) population, we believe that in the near future we can draw a nice outline of how gut microbiota can predict behavior – and possible mental health disorders – in individuals who are currently healthy.