GUT FEELINGS: THE ROLE OF THE MICROBIOME IN BRAIN FUNCTION AND BEHAVIOR - SYSTEMATIC REVIEW

Background: The gut microbiome is a very dynamic and complicated ecosystem that has a key role to play in the regulation of the brain and behavior through the use of the gut-brain axis. This two-way communication system affects neurological development, mental health, thinking, and behavior through immune signaling, microbe-derived metabolites, neurotransmitters, and through Vagal circuits.
Objective: The purpose of this systematic review is to summarize the existing evidence of the effect of gut microbiome on brain functioning, the way it develops over different stages of life, its involvement in mental disorders, and the possibility of therapy based on microbiome regulation.
Methods: Following the PRISMA requirements, the literature was searched in the PubMed, Scopus, and Web of Science databases and limited to the period of 2015-2025 to find the studies. Articles that focused on associations between gut microbiota, gut-brain axis, neurodevelopment, neurodegeneration, psychiatric diseases, and microbiome-based treatments were included in the review.
Results: The review points to several mechanisms by which the gut microbiome influences the brain, one of them being short-chain fatty acid (SCFA) production, neurotransmitter production, immune regulation, and the vagal pathway. The brain maturation and cognitive outcomes depend on early-life microbiome composition, which has a profound influence. There is a lot of evidence of an intense relationship between dysbiosis and neurodevelopmental, neuropsychiatric, and neurodegenerative conditions. Probiotics-based interventions, prebiotic interventions, dietary modulation, and fecal microbiota transplantation all hold therapeutic promise.
Conclusion: The gut microbiome makes considerable contributions to the regulation of brain activity and behavior throughout the life cycle, and these connections are complex physiological mechanisms. Although proceeding research suggests new treatment possibilities in neurological and psychiatric diseases, some difficulties are associated with methodological heterogeneity, variability of microbiome in different people, and a lack of understanding of the mechanisms.

Keywords: Gut Microbiome, Neurodevelopment, Neurotransmitters, Cognitive functions, Gut-Brain axis.