Probiotics Role in Gut-Brain Axis: A Novel Insight of Microbiota Involving Neurodegenerative Disorders

The gut-brain axis (GBA) serves as a intricate two-way communication system that links gastrointestinal tract and the central nervous system (CNS) through neural, endocrine, immune, and metabolic pathways.The growing evidence highlights the crucial role of gut microbiota in regulating stress responses, cognitive functions, mood, and neurodegenerative processes.Dysbiosis of the gut microbiome has been strongly associated with several psychiatric and neurological disorders, including depression, anxiety, autism spectrum disorder, Alzheimer's disease, and Parkinson's disease.Probiotic strains with psychobiotic potential, particularly members of the Lactobacillus and Bifidobacterium genera, have shown favourable effects by modulating the hypothalamic-pituitary-adrenal (HPA) axis, enhancing the intestinal barrier integrity, and producing neuroactive metabolites such as short-chain fatty acids (SCFAs).These metabolites influence neurotransmitter pathways involved in serotonin, gamma-aminobutyric acid (GABA), and dopamine synthesis, thereby contributing to improved neurochemical balance and mental health outcomes.In addition to conventional probiotics, emerging strategies including engineered probiotics, customized microbiomebased therapies, and multi-omics technologies offer promising precision-based approaches to modulate host-microbe interactions.Diet marks a fundamental role in tailoring the gut microbiota composition, with dietary fibers and polyphenols promoting neuroprotective effects through microbial metabolite production.This review highlights the therapeutic potential of probiotics in GBA modulation while addressing emerging innovations and challenges for their translation into clinical practice.