Psychiatry researchJun 18, 2023

Gut and mouth bacteria linked to molecular and clinical signs of schizophrenia symptoms across diagnoses

Gut-Brain Axis Weekly Brief ↗PubMed ↗DOI ↗

Updated Apr 3, 2026

Abstract

Psychiatric cases exhibited significantly greater heterogeneity of gut alpha diversity and enrichment of pathogenic taxa in the oral microbiome.

Gut microbial diversity was found to be more variable among psychiatric cases compared to nonpsychiatric controls.
Pathogenic bacteria, such as Veillonella and Prevotella, were more prevalent in the oral microbiome of individuals with psychiatric symptoms.
Positive, negative, and general symptoms measured by the Positive and Negative Syndrome Scale (PANSS) correlated with specific bacterial taxa.
Correlations were also identified between bacterial taxa and inflammatory markers in the blood, as well as hippocampal inflammation and altered brain signaling.
These findings support the hypothesis that the microbiome-gut-brain axis may play a role in the manifestation of psychiatric symptoms.

Simplified

Although increasing evidence links microbial dysbiosis with the risk for psychiatric symptoms through the microbiome-gut-brain axis (MGBA), the specific mechanisms remain poorly characterized. In a diagnostically heterogeneous group of treated psychiatric cases and nonpsychiatric controls, we characterized the gut and oral microbiome, plasma cytokines, and hippocampal inflammatory processes via proton magnetic resonance spectroscopic imaging (H-MRSI). Using a transdiagnostic approach, these data were examined in association with schizophrenia-related symptoms measured by the Positive and Negative Syndrome Scale (PANSS). Psychiatric cases had significantly greater heterogeneity of gut alpha diversity and an enrichment of pathogenic taxa, like Veillonella and Prevotella, in the oral microbiome, which was an accurate classifier of phenotype. Cases exhibited significantly greater positive, negative, and general PANSS scores that uniquely correlated with bacterial taxa. Strong, positive correlations of bacterial taxa were also found with cytokines and hippocampal gliosis, dysmyelination, and excitatory neurotransmission. This pilot study supports the hypothesis that the MGBA influences psychiatric symptomatology in a transdiagnostic manner. The relative importance of the oral microbiome in peripheral and hippocampal inflammatory pathways was highlighted, suggesting opportunities for probiotics and oral health to diagnose and treat psychiatric conditions. 1

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Competing interests

Declaration of Competing Interest JCC, OG, and DM were supported by NIH NIMH grant 5R01MH110418. JJL is supported by NIH TL1 grant 5TL1RR029886. OG and EL are also supported by NIH NIBIB grant P41 EB017183. Computational analysis was supported by Mount Sinai's Scientific Computing through an allocation to JCC. All authors declare no conflicts of interest.

PubMed

Gut and mouth bacteria linked to molecular and clinical signs of schizophrenia symptoms across diagnoses

Abstract

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