Role of Gut Microbiota in Psychiatric Disorders: From Mechanistic Insights to Therapeutic Strategies

Mental health disorders are a global health challenge, and the underlying biological mechanisms remain unclear. Recent evidence has linked gut microbiota to psychiatric symptoms through complex bidirectional interactions along the gut-brain axis, which involve neural, endocrine, and immune pathways. This narrative review aims to synthesize current findings on how gut microbiota contributes to the pathophysiology of major psychiatric disorders, and explore microbiota-based therapeutic interventions, and discusses emerging strategies for personalized treatment. Relevant literature up to July 2025 was reviewed using targeted keywords in major databases, including PubMed and Google Scholar. Rather than applying formal systematic review criteria, we focused on selecting influential and high-impact studies, and the findings were synthesized thematically to provide a comprehensive overview. Consistent findings across psychiatric conditions include a decreased abundance of short-chain fatty acid-producing bacteria and an increased presence of pro-inflammatory taxa. These shifts correlate with heightened systemic inflammation, disrupted neurotransmitter synthesis, and dysregulation of the hypothalamic-pituitary-adrenal axis. Thus, the gut microbiota is increasingly recognized as playing a potential role in the pathophysiology of psychiatric disorders through multifaceted mechanisms involving the gut-brain axis. Probiotics, prebiotics, and dietary modifications show promise in modulating gut microbiota and alleviating psychiatric symptoms, although clinical outcomes remain heterogeneous. Emerging precision medicine strategies indicate promising potential for personalized microbiota-based treatments. Although microbiota-targeted therapies offer promising adjunctive strategies, large-scale, mechanistically informed clinical trials remain warranted. Future research should leverage artificial intelligence and multi-omics tools to develop personalized interventions tailored to individual microbiome profiles.