Role of the gut-brain axis in neurological diseases: Molecular connections and therapeutic implications (Review).

The gut-brain axis, a bidirectional communication system involving the central nervous system, enteric nervous system and gastrointestinal tract, plays a pivotal role in neurological health and disease. The present review synthesizes current evidence on its anatomical foundations, functional mechanisms and the role of gut microbiota in neurological diseases. It is explored how dysregulation of the gut-brain axis contributes to neurodegenerative, neuroinflammatory, neurodevelopmental, cerebrovascular and epileptic disorders through molecular mechanisms including neuroinflammation, neurotransmitter modulation, oxidative stress, and blood-brain barrier changes. Furthermore, therapeutic strategies targeting this axis, such as dietary interventions, probiotics, pharmacological approaches and emerging therapies were evaluated. The present review highlights the potential for developing biomarkers and personalized medicine approaches based on gut-brain axis components, while acknowledging translational challenges. However, significant heterogeneity in probiotic strains, FMT protocols, and patient microbiota baselines limits immediate translation. Future trials must address these variables through standardized designs and multi-omics biomarker integration.