Gut microbiota in neurological and psychiatric disorders: A review study

Introduction: The gut microbiota, consisting of trillions of microorganisms residing in the gastrointestinal tract,has emerged as a complex ecosystem with a profound influence on human health and disease. Recent studieshave implicated the gut-brain axis, a bidirectional communication pathway between the gut and the centralnervous system, in the pathogenesis and progression of various neurological disorders. This systematic reviewaims to explore the current body of literature investigating the interplay between gut microbiota and neurologicaland psychiatric disorders, with a focus on understanding the potential mechanisms underlying their association.Methods: A comprehensive systematic search was done in electronic databases, including PubMed, Web ofScience and Scopus, using relevant keywords such as "gut microbiota", "neurological disorders" and"psychiatric disorders". Studies published until ۲۰۲۳ were included. The screening process involved specificcriteria, and data were extracted and analyzed.Results: A number of studies met the inclusion criteria. The findings from the included studies demonstratedalterations in the gut microbiota composition and disorders such as depression, anxiety, bipolar disorder, autism,schizophrenia, Parkinson, Alzheimer, dementia, multiple sclerosis, epilepsy and migraine, by underlyingmechanisms including immune system modulation, metabolism of neurotransmitters, and alterations in theblood-brain barrier integrity. Furthermore, microbiota-based interventions, such as probiotics and fecalmicrobiota transplantation, showed promise in ameliorating symptoms in preclinical models and small-scaleclinical trials.Conclusion: This systematic review highlights the significant association between gut microbiota andneurological and psychiatric disorders. Furthermore, Modulating the gut microbiota through targetedinterventions represents a potential therapeutic avenue for managing the mentioned disorders. However, furtherresearch is needed to elucidate the complex interactions between gut microbiota, host physiology, and thementioned disorders outcomes, as well as to establish standardized protocols for microbiota-based therapies.