Disruption of the Gut Microbiome and Mental Health Effects Connected to Environmental Pollutants via the Gut-Brain Axis

Environmental pollutants, including heavy metals, endocrine-disrupting chemicals, persistent organic pollutants, microplastics, and particulate matter, are increasingly recognized as key modifiers of the gut microbiome. These exposures can induce dysbiosis, disrupting the microbiota-gut-brain axis and influencing neurodevelopment, neurotransmission, immune regulation, and behavior. Mechanistically, pollutant-induced alterations in microbial metabolites (e.g., short-chain fatty acids, indoles, and bile acids), intestinal permeability, neuroinflammation, vagal signaling, and activation of the hypothalamic-pituitary-adrenal axis contribute to adverse neurobehavioral outcomes. Evidence from human cohort studies and animal models supports associations between pollutant exposure, microbial functional changes, and cognitive or mental health effects. This review synthesizes current mechanistic insights, highlighting advances in exposomic, microbial xenobiotic metabolism, and microbiome-targeted interventions to mitigate neurotoxicity. While these findings offer promising directions for risk assessment and therapeutic development, human evidence remains limited, and quantitative links between microbiome alterations and neurobehavioral outcomes require further investigation.