An Updated and Comprehensive Review Exploring the Gut–Brain Axis in Neurodegenerative Disorders and Neurotraumas: Implications for Therapeutic Strategies

The gut–brain axis (GBA) refers to the biochemical bidirectional communication between the central nervous system (CNS) and the gastrointestinal tract, linking brain and gut functions. It comprises a complex network of interactions involving the endocrine, immune, autonomic, and enteric nervous systems. The balance of this bidirectional pathway depends on the composition of the gut microbiome and its metabolites. While the causes of neurodegenerative diseases (NDDs) vary, the gut microbiome plays a crucial role in their development and prognosis. NDDs are often associated with an inflammation-related gut microbiome. However, restoring balance to the gut microbiome and reducing inflammation may have therapeutic benefits. In particular, introducing short-chain fatty acid-producing bacteria, key metabolites that support gut homeostasis, can help counteract the inflammatory microbiome. This strong pathological link between the gut and NDDs underscores the gut–brain axis (GBA) as a promising target for therapeutic intervention. This review, by scrutinizing the more recent original research articles published in PubMed (MEDLINE) database, emphasizes the emerging notion that GBA is an equally important pathological marker for neurological movement disorders, particularly in Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, Huntington’s disease and neurotraumatic disorders such as traumatic brain injury and spinal cord injury. Additionally, the GBA presents a promising therapeutic target for managing these diseases.