The secret to having psychopathic traits could have something to do with gut bacteria. That’s the provocative claim of a new study published as an early-release, peer-reviewed paper in Translational Psychiatry.
To test the hypothesis, a team led by Carolina Costa, a biomedical scientist at the University of Porto, recruited two hundred adults to fill out a questionnaire built to measure psychopathic traits, then collected saliva and fecal samples for microbiota analysis, along with blood samples for metabolic markers
“We hypothesized that the composition of the gut and oral microbiota may be associated with subclinical psychopathic personality traits… To our knowledge, this is the first study to explore this association,” the researchers wrote.
That association did not show up as a clear difference in overall microbial diversity between groups. Nonetheless, several individual microbes did stand out. Allisonella, Prevotella, and C. evryensis, for instance, were associated with higher psychopathy scores, while T. vincentii was associated with lower scores.
What these specific microbes actually do
Allisonella has been connected to human disease and inflammation, which the team says is a key factor in psychiatric disorders such as anxiety and depression.
Prevotella, meanwhile, has been linked in earlier research to differences in brain regions involved in emotional, attentional, and sensory processing, including “less specificity of encoding the contextual details of incoming stimuli,” in other words, a reduced ability to accurately take in and distinguish the surrounding details of a situation.
But these possible biological links come with major caveats.
The study involved just two hundred people, which is a small sample to build much on. Then there’s the fact that the psychopathy scores came from the participants themselves rather than any clinical assessment, and it was all conducted in a single setting.
The researchers also note that the results might look different depending on the geographical location of participants. As they put it, “Finally, as findings are correlational, causality cannot be established, especially given the bidirectionality of microbiota-brain communication.”
Nobody can say which way the arrow points, in other words. The team raises the possibility that psychopathy-linked factors like eating behavior and hormonal differences are what shape the gut microbiota, rather than the microbiota shaping anything.
Still, the broader idea that biology plays some role in psychopathic traits is not new. Earlier research has found shared brain structures among people with psychopathic traits, including pathways in the prefrontal cortex.
Whether this link turns out to be meaningful or incidental will take much bigger studies to sort out