Kuntz, T. M. | bioRxiv Science

bioRxiv2025

Item recognition is associated with gut microbiota composition in healthy humans

Murine studies show that the gut microbiota - the collection of the microbes residing in the large intestine - affects memory performance in the host. However, whether commensal gut bacteria are linked to human episodic memory remains unknown. Here, we investigated whether individual differences in episodic memory performance were associated with differences in the indigenous gut microbiota composition between individuals. We show that greater gut microbiota alpha diversity was associated with better item recognition and that gut microbiota dissimilarity index (beta diversity) between participants was associated with differences in their performance. Finally, our results suggest that Prevotella copri might play a role in the relationship between gut microbiota and human item recognition in healthy individuals. In a sample size larger than previous human studies and examining unmanipulated gut microbiota, we provide evidence that episodic memory in healthy humans is linked to their gut microbiota composition. SIGNIFICANCE STATEMENTUnderstanding the relationship between the gut microbiota - the collective of microbes in our gut - and human cognition represents a pivotal frontier in neuroscience. Our study dives into this quest by exploring the connection between the indigenous gut microbiota and episodic memory in healthy individuals. While prior research has illuminated this relationship in murine models, our study extends these findings to humans, providing compelling evidence that gut microbiota diversity and structural composition are associated with differences in episodic memory performance. By shifting the focus from probiotic-based interventions to the study of our commensal gut microbes, our findings shed light on how the gut microbiota, in its natural state, could be linked to interindividual differences in human cognition.

animal behavior and cognition↗

bioRxiv2022

Human threat learning is associated with gut microbiota composition

Rodent studies have shown that the gut microbiota can influence threat and safety learning, which has been linked to anxiety phenotypes. In humans, it has been demonstrated that microbiota composition varies with anxiety disorders, but evidence showing an association with threat learning is lacking. Here, we tested whether individual variability in threat and safety learning was related to gut microbiota composition in healthy adults. We found that threat, but not safety learning varies with individuals microbiome composition. Our results provide evidence that the gut microbiota is associated with excitatory threat learning across species. Significance StatementLearning from threats and safety is a core mechanism of anxiety disorders, and studies in rodent models have shown that the gut microbiota can modulate such behaviors. Although previous literature on humans shows a relationship between emotional circuits and gut microbiota, the evidence linking learning and microbiota is lacking. In a Pavlovian threat conditioning paradigm, we show that patterns of gut microbiota composition in healthy humans relate to their patterns of threat learning, but not safety learning. Our findings suggest one mechanism by which the human gut microbiota is associated with anxiety-related behaviors.

animal behavior and cognition↗