The gut microbiome of youth who have behavioral and mental health problems: A scoping review

Objective

Mental health problems among youth have increased significantly over the past several decades. While there is growing evidence that the gut microbiome may be an important mechanism affecting mental health, results of the limited studies focused on children, adolescents, and young adults have not been synthesized. This scoping review examined existing literature to identify key findings on the associations between the gut microbiome and mental health of youth.

Methods

A literature search using PubMed, PsycINFO, and CINAHL was performed, and bibliographies were manually searched. Eighteen articles met eligibility for the review. Findings from each study were evaluated, focusing on associations of specific mental health problems to bacterial composition and diversity among youth. There were no studies solely on the adolescent age group, so data was synthesized comparing the child/adolescent (2 to <18 years of age) and young adult (18–25 years of age) groups.

Results

Most studies utilized 16S rRNA for gut microbiome analysis, and various mental health conditions were examined. Findings for both age groups were mostly inconsistent. However, bifidobacteria was generally associated with better mental health across age groups. Diversity of microorganisms was decreased for children/adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD) and high levels of stress but increased for young adults with ADHD and Major Depressive Disorder.

Conclusion

Future research should replicate studies to clarify findings, examine species-level effects and their functions, consider longitudinal designs to assess directionality of associations, and conduct clinical trials to examine the effects of putative probiotics in the management of psychological symptoms.