An early-release study in Translational Psychiatry reports correlations between specific gut and oral bacteria and scores on a psychopathy questionnaire in 200 healthy adults. Higher abundance of Allisonella, Prevotella and Cloacibacillus evryensis correlated with stronger psychopathic traits, while oral Treponema vincentii showed an inverse association. The findings are correlational, the paper is pending peer review, and further research is needed to test causation and mechanisms.
Gut and Oral Microbes Linked to Psychopathic Traits, Early Study Finds
(Alexander Krivitskiy/Unsplash)
New research suggests the microbes living in our gut and mouth may be linked to personality traits associated with psychopathy. An early-release study in Translational Psychiatry reports correlations between the abundance of several bacterial taxa and scores on a psychopathy questionnaire — though the authors stress these findings are preliminary and do not prove causation.
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Study Design
Biomedical scientist Carolina Costa and colleagues at the University of Porto recruited 200 healthy adults. Each participant completed the Self-Report Psychopathy Scale–Short Form and provided blood, saliva and fecal samples. The team analysed bacterial composition and metabolic markers from those biological samples to explore associations with subclinical psychopathic traits.
Psychopathy is a personality construct marked by lack of empathy, antisocial tendencies, impulsiveness, and egoism. (disqis/Getty Images)
Key Findings
When comparing individuals with one another (inter-individual analysis), the researchers found that higher abundance of three taxa correlated with stronger psychopathy markers: Allisonella and Prevotella (gut genera) and the species Cloacibacillus evryensis. By contrast, greater levels of the oral species Treponema vincentii were associated with lower psychopathy scores.
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"The associations we observed, particularly between specific taxa (e.g., Allisonella, Prevotella, C. evryensis, T. vincentii) and traits such as callousness, manipulation, impulsivity, and anti-sociality, suggest a measurable biological footprint for psychopathy that extends beyond traditional neurocognitive models," the authors write.
Possible Mechanisms
The paper discusses several hypotheses that could link microbes to behavior: Allisonella has been associated with inflammatory states (and inflammation has known links to mood and behavior), Prevotella has prior ties to neuropsychiatric conditions and emotional processing, and C. evryensis may influence levels of the inhibitory neurotransmitter GABA, which plays a role in impulse control. These are plausible mechanisms but remain speculative without causal evidence.
Limitations
Important caveats apply: this is an early-release paper pending peer review, the study reports correlations rather than causation, and the sample—200 healthy adults—may not represent clinical populations. The researchers also did not find straightforward links when examining within-person microbial diversity, and the negative association for T. vincentii lacks a clear explanation.
What This Means
The study offers intriguing leads that microbial composition and microbial metabolites could one day serve as biomarkers for certain personality traits. However, replication, longitudinal work, mechanistic experiments, and clinical studies are needed before drawing firm conclusions or considering diagnostic applications.
Bottom line: The microbiome may be one piece of a complex biological puzzle behind psychopathic traits, but current evidence is preliminary and should be interpreted cautiously.
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