Probiotics as a Complementary Medicine in Neurologic Disorders.

Background and Aims: Today, neurological and neuropsychiatric disorders, including depression, anxiety, Parkinson's disease (PD), Alzheimer's disease (AS), autism spectrum disorder (ASD), and multiple sclerosis (MS), contribute significantly to global disability and healthcare burden. Most current treatment options only provide symptomatic relief and are limited by challenges such as drug resistance, systemic side effects, and poor blood-brain barrier permeability. The growing interest in the gut-brain axis has encouraged exploration of the gut microbiota as a potential therapeutic target. Probiotics-live microorganisms that may confer health benefits to the host-have been proposed to modulate the gut-brain axis through immune, metabolic, and neurochemical pathways. Methods: In this narrative review, a targeted search was performed across multiple databases to identify relevant articles, from which the key relationships and strategies were extracted. Then, we represented the findings to provide a comprehensive overview of the topic and highlight emerging trends and gaps in the literature. Results: Emerging preclinical and clinical studies suggest that specific probiotic strains can improve neurological symptoms by reducing neuroinflammation, supporting gut barrier integrity, and influencing neurotransmitter production. However, findings remain heterogeneous due to strain specificity, individual microbiome diversity, and methodological differences across studies. Preclinical and clinical studies suggest that specific probiotic strains can improve neurological symptoms by reducing neuroinflammation, enhancing gut barrier integrity, and influencing neurotransmitter production. Evidence supports their potential as adjunctive treatments for major neurological and neuropsychiatric disorders, including depression, anxiety, ASD, PD, AD, and MS, particularly in patients with gut dysbiosis or gastrointestinal comorbidities. However, findings remain heterogeneous due to strain specificity, individual microbiome variability, and methodological differences across studies. Conclusion: This brief review summarizes the current evidence on the use of probiotics in neurological disorders, discusses potential mechanisms of action, and highlights safety considerations and limitations. Future directions include personalized probiotic therapies, large-scale randomized controlled trials, and integration with conventional neurological therapies. Overall, probiotics could be a low-risk, complementary option in the evolving field of neurotherapy, but more rigorous evidence is needed before definitive clinical recommendations can be made.