Altered oral microbiome composition in mental disorders: a systematic review and meta-analysis

Area of Science:

• Microbiome research
• Neuroscience
• Mental health

Background:

• The gut-brain axis is implicated in mental disorders, but the oral microbiome's role is understudied.
• Oral microbial signatures may offer insights into mental disorder pathophysiology.
• Investigating the oral microbiome could lead to new diagnostic biomarkers and treatments.

Purpose of the Study:

• To systematically review and meta-analyze oral microbiota alterations in six mental disorders.
• To synthesize data from case-control studies to compare oral microbial diversity between patients and controls.

Main Methods:

• Systematic review and meta-analysis of 20 case-control studies from PubMed, Embase, and Cochrane Library.
• Extraction of relative microbial abundance and beta diversity indices.
• Random-effects meta-analyses for alpha diversity to compare patients and controls.

Main Results:

• A significantly higher Simpson Index was observed in patients compared to controls (SMD = 0.42).
• Beta diversity differed significantly in schizophrenia (SZ) and major depressive disorder (MDD).
• Specific microbial changes included *Rothia* enrichment in autism spectrum disorder (ASD), H2S-producing genera in SZ, and reduced *Solobacterium* and *Leptotrichia* in MDD.

Conclusions:

• Oral microbiota diversity is altered across various mental disorders.
• Disease-associated microbial shifts suggest the oral microbiome's potential role in mental health.
• Further research is warranted for diagnostic and therapeutic applications targeting the oral microbiome.