The Microbiota-Gut-Brain Connection: A New Horizon in Neurological and Neuropsychiatric Disorders

Abstract

Introduction: The microbiota-gut-brain axis (MGBA), a complex two-way connection between the gut microbiota and the brain, has become a key regulator of neurological and neuropsychiatric disorders. Neurological disorders and gut microbiota dysbiosis are linked to these diseases. Changes in gut microbiota can lead to neurotransmitter imbalances, oxidative stress, and neuroinflammation. Gut dysbiosis may contribute to the development of diseases such as depression, autism, schizophrenia, bipolar disorder, Parkinson's disease, Alzheimer's disease, dementia, multiple sclerosis, epilepsy, anxiety, and autism spectrum disorders through immunological regulation, neuroinflammation, and neurotransmitter metabolism changes.

Method: This review systematically sourced articles related to microbiota gut brain axis, neurological disorders, neuropsychiatric disorders and clinical studies from major medical databases, including Scopus, PubMed, and Web of Science.

Results: This review explores the molecular processes underlying MGBA interactions, including vagus nerve signaling, systemic immunological responses, and metabolites produced by microorganisms. The discussion explores the potential of microbiome-targeted treatments like fecal microbiota transplantation, probiotics, and prebiotics as effective treatment methods. The comprehension of the MGBA can revolutionize neurology and psychiatry, introducing innovative diagnostic and therapeutic approaches. Multiple elements, including diet, metabolism, age, stress, and medications, shape the human gut microbiota, and intestinal imbalances can lead to CNS diseases. The MGBA interacts with gut bacteria, and gut dysbiosis is associated with neurological disorders.

Conclusions: The review demonstrates the correlation between gut microbiota and neurologically associated diseases, highlighting its importance in neurogenesis, mental development, emotions, and behaviors. MGBA, mediated by microbial metabolites, affects brain function and neuroinflammation. Interventions like fetal microbiota transplantation, probiotics, and prebiotics can improve microbial balance, but more clinical research is needed.

Keywords: gut dysbiosis; microbiota‐gut‐brain axis; neuroinflammation; neurological disorders; neuropsychiatric disorders; probiotics.

FIGURE 1

The MGBA is a complex communication network between the gut microbiota and the CNS, affecting brain function and behavior. Mutations in the gut microbiota may be a factor in neurological and neuropsychiatric disorders like ASD, AD, PD, and anxiety.

FIGURE 2

The MGBA is a key player in the pathophysiology of ASD, with behavioral symptoms and neurodevelopmental problems influenced by changes in gut permeability, immunological responses, microbial metabolites, and gut microbiota composition. Mechanisms connecting ASD to the MGBA include immune dysregulation, neuroinflammation, neurotransmitter imbalance, and stress response. Therapeutic interventions targeting the MGBA include probiotics, prebiotics, fetal microbiota transplantation, and nutritional measures like omega‐3 fatty acids.

FIGURE 3

AD is influenced by hereditary and environmental factors, with the MGBA playing a major role.

FIGURE 4

Gut dysbiosis contributes to PD by increasing intestinal permeability, reducing butyrate‐producing bacteria, and weakening the intestinal mucus layer. This leads to toxin exposure, aberrant α‐synuclein fibril aggregation, and neuroinflammation in the CNS.