Microbiota–brain axis: Context and causality

Abstract

The gut microbiota is associated with brain development and function, as well as altered emotional, motor, and cognitive behaviors in animals. However, there remains a pressing need to unravel the mechanisms and pathways of communication that underpin microbiota-brain connections. Reductionist animal models have revealed profound contributions by gut bacteria to brain activity and behavior, although the extent to which these findings translate to humans is largely unclear. Associations between fecal microbiome profiles and human behavior and neurological diseases are prevalent. Longitudinal studies that integrate genetic, environmental, and experiential factors in shaping and responding to gut microbial functions, as well as interventions that modify microbiota-brain interactions at the cellular and molecular level, will help resolve contexts in which microbes may influence the human brain and its health. Accordingly, prospects for targeting the gut, rather than the brain, to improve altered behaviors or brain pathologies appear both feasible and timely.

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