Behavioral evidence of the role of the gut microbiota on fear processing in women affected by obesity

Microbiota-gut-brain axis may extend beyond visceral perception, influencing higher-order brain structures, and ultimately psychological functions such as fear processing. In this work, we provided novel experimental evidence on the relationship between gut microbiota composition and diversity, and fear processing in obesity, through a behavioral approach. Twenty women affected by obesity were enrolled and profiled for gut microbiota (through 16S rRNA amplicon sequencing) and their ability to recognize facial fearful expressions through the implicit facial emotion recognition task). Moreover, we assessed their temperament through a traditional self-report questionnaire. Our participants exhibited an unbalanced gut microbiota profile along with impaired recognition of fearful expressions. Interestingly, the dysbiosis was overall more severe in women with an altered behavioral performance, with notably an increase in the pathobiont Collinsella, and a decrease in typically health-associated microbes. Interestingly, we documented a relationship between Collinsella and the expression of the temperamental traits in our sample. This represents the first investigation of gut microbiota and fear-related behavior in human obesity. In addition to increasing our knowledge of the potential role of the gut microbiota in psychological functioning, and specifically fear-related processes, our findings could pave the way for the design of innovative microbiota-based strategies for treating psychological and emotional difficulties by mitigating obesity-related consequences and behaviors.