New research published in Translational Psychiatry suggests a link between the human microbiome and psychopathic personality traits. A study led by Carolina Costa at the University of Porto found that specific bacterial compositions in the gut and oral cavity correlate with traits such as impulsivity, callousness, and antisocial behavior. While these findings do not establish causation, they offer a potential biological marker for psychopathic tendencies that traditional neurocognitive models may overlook.
Microbiome Composition and Psychopathic Traits
Researchers examined 200 healthy adults to determine if microbial diversity influences personality. Participants completed the Self-Report Psychopathy Scale-Short Form and provided blood, saliva, and fecal samples for analysis. According to the study, while overall microbial diversity did not show a clear link to psychopathy, specific bacterial genera showed a positive association with psychopathic traits.
The study identified three specific bacteria—Allisonella, Prevotella, and Cloacibacillus evryensis—that appeared more frequently in individuals scoring higher on psychopathy markers. Conversely, the oral bacterium Treponema vincentii showed a negative association, appearing more often in participants with lower psychopathy scores. The research team noted that these findings suggest a “measurable biological footprint” that may complement existing brain-based theories of psychopathy.
Biological Mechanisms and Behavioral Links
The researchers hypothesize that these microbes may influence behavior through metabolic outputs. Allisonella has been linked to human diseases and potential inflammation, which the study authors suggest could play a role in its possible role in psychopathy. Prevotella is similarly associated with neuropsychiatric disorders and is thought to affect emotional processing.
The presence of C. evryensis is particularly noteworthy due to its suspected role in producing gamma-aminobutyric acid (GABA). As an inhibitory neurotransmitter, GABA is involved in systems that regulate impulse control. The researchers propose that these biological pathways offer new avenues for understanding why traditional brain structure models, such as those involving the prefrontal cortex, may provide an incomplete picture of psychopathic behavior.
Future Directions for Clinical Diagnostics
The study by Carolina Costa and her colleagues represents an early step in identifying how the body’s internal ecosystem might reflect personality constructs. Because this is the first study to explore the association between microbiota and subclinical psychopathic personality traits, the findings have yet to undergo peer review. Experts emphasize that these results currently only highlight correlations rather than direct causes.
If future research confirms these associations, clinicians could potentially use metabolic outputs from the microbiome as biomarkers to identify individuals who show these dark impulses.
Frequently Asked Questions
Can gut bacteria cause someone to become a psychopath?
Further research is required to determine if a causal relationship exists.
What specific bacteria were linked to psychopathic traits?
The researchers found that higher abundances of Allisonella, Prevotella, and Cloacibacillus evryensis were positively associated with psychopathic traits in the study population.
Is this research peer-reviewed?
The study was published in Translational Psychiatry as an early-release version and has not yet undergone full peer review.
What are your thoughts on the connection between our internal biology and personality? Share your perspective in the comments below or subscribe to our newsletter for the latest updates on emerging neuroscience and microbiome research.
Related reading