What is already known
The connection between the gut microbiome and the brain has become a topic of significant interest in the scientific and public community, as it might provide insights into the development of mental health problems (i.e psychiatric disorders). Indeed, differences in gut microbiome composition have been associated with mental health issues, although most of the evidences come from animal studies or human studies with modest sample sizes.
What this research adds
Researchers investigated the correlation between the gut microbiome and mental health problems in a multi-ethnic cohort of 1,784 ten-year-old children and observed a decrease, although not significant, in the diversity of the gut microbiome in individuals with higher mental health issues. Differences in compositional genera abundance were also observed and found to be consistent across all types of mental health issues. However, no significant correlation was revealed between neither taxonomic characteristic nor specific microbial functions and mental health problems.
The findings suggest a reduction in certain genera such as Hungatella, Anaerotruncus, and Oscillospiraceae, which have been previously associated with psychiatric disorders, but no compelling evidence of connections between diversity, taxonomies, or functions of the gut microbiome and mental health issues in the general pediatric population.
The gut microbiome has gained significant attention due to its potential role in mediating communication between the gut and the brain, known as the gut-brain axis. The gut microbiome affects the brain through various pathways, such as neurotransmitter synthesis, immune system activation and production of neuroactive metabolites.
A cross-sectional study lead by Robert Kraaij and colleagues, and published in Brain, Behavior and Immunity journal, suggests that psychiatric symptoms, emotional and behavioral problems are not strongly associated with gut microbiome composition and function in pediatric population.
To examine the association between the gut microbiome and common mental health problems in children, researchers at the Erasmus University Medical Center in the Netherlands, performed 16S rRNA sequencing of the gut microbiome from stool samples from 10-year-old kids and assessed their mental health problems using the Child Behavior checklist rated by mothers.
Child mental health problems and gut microbiome diversities
After adjusting for age, sex, BMI, self-reported use of antibiotics, maternal education, technical covariates, no associations were observed between overall mental health problems and gut microbiome richness or diversity indices. Although most associations were negative, indicating that greater mental health issues were related to lower microbiome diversity, data were not significant. Follow-up analyses focusing on specific mental health problems showed similar findings.
Child mental health problems and gut microbiome profiles and function
Researchers also investigated whether single taxonomies could be associated with child mental health problems and identified six genera associated with either overall or specific mental health issues (i.e., Muribaculaceae unknown genus, Erysipelatoclostridium, Eubacterium ruminantium group, Hungatella, Anaerotruncus, and Oscillospiraceae unknown genus).
The team further investigated the association between overall gut microbiome composition and function and mental problems in children, but no significant associations were detected.
Although generally lower gut microbial diversity and richness was linked to more overall (e.g. internalizing problems) and specific (e.g. anxious/depressed behavior) problems, data were not significant. These findings are consistent with other population-based studies on the link between gut microbiome and mental health, which also reported weak associations with Alpha diversity indices in children and adults.
The authors highlighted three genera that were consistently associated with child mental health issues: Hungatella, Anaerotruncus, and Oscillospiraceae. Increased abundance of Hungatella was associated with somatic complaints, while Anaerotruncus was associated with more internalizing problems and somatic complaints. Finally, Oscillospiraceae was linked to more child aggressive problems, which contrasts with previous findings that have linked lower abundance of this genus with major depressive disorder in adults.
In contrast with the current literature, the present study revealed no clear evidence linking the gut microbiome to mental health problems in children. However, researchers do not definitively refute a link, but indicate that any associations are likely to be small in the general pediatric population at this age. Future research should focus on longitudinal data from early life to adulthood, examining associations with autism spectrum disorder (ASD), and characterizing how the gut microbiome associates with individual differences within the brain in vivo during development. Finally, collaborative initiatives would be needed to detect subtle associations and understand the role of the gut microbiome in the development of psychiatric symptoms over time.