Gut Microbiota and Anxiety: A Mechanistic Study of Human Infants

Experimental manipulation of gut microbes in animal models alters fear behavior and relevant neurocircuitry. In humans, the first year of life is a key period for brain development, the emergence of fearfulness, and the establishment of the gut microbiome. Variation in the infant gut microbiome has previously been linked to cognitive development, but its relationship with fear behavior and neurocircuitry is unknown. In this prospective longitudinal cohort study, we recruited 34 infants at 1 month and 1 year of age to test for associations between the gut microbiome, fear behavior, and fear neurocircuitry. To reduce confounding effects of birth mode, antibiotic exposure, and feeding practices, all infants were vaginally delivered, antibiotic naïve, and exclusively breastfed until their first study visit at 1 month.