The role of the microbiota in neurological diseases

Growing evidence has directly linked the gastrointestinal tract, gut microbiota, and central nervous system, forming the gut-brain axis, a process that has been described as a key mechanism in regulating neurological processes. However, the presence of alterations in the composition of microorganisms in the digestive tract and dysbiosis has been linked to the activation of microglia, increased oxidative stress, alterations in the production of neurotransmitters, and exacerbation of neuroinflammation. These mechanisms have been associated with multiple pathologies and neurological conditions, and regulating them is key to the control of these diseases. In this context, various bacterial species play a neuroprotective role by promoting the integrity of the intestinal barrier, stimulating the synthesis of beneficial metabolites such as short-chain fatty acids (SCFAs), neurotransmitters, and modulating the inflammatory response. In addition, the characterization of these microbial profiles provides a broad perspective on understanding how changes in the microbiota contribute to the progression of neurological diseases. On the other hand, these new updates open up the possibility of designing personalised targeted therapeutic interventions that can regulate the gut microbiota and promote a neuroprotective and neuroregenerative environment. Another key point is that greater emphasis is placed on the need for more controlled clinical studies to validate efficacy and safety in humans, as well as knowledge of the mechanisms of action that make them possible. Finally, the modulation of the gut microbiota using probiotics, prebiotics, and postbiotics represents an innovative and effective opportunity to intervene in neuroimmune processes such as microglial activation, regulation of synaptic pruning, and neuroinflammatory pathways—processes implicated in various neurological diseases. In this context, this review integrates and analyzes the available evidence, highlighting potential interventions as treatments for these pathologies, as well as current limitations, to provide an updated framework to guide future research.