The emerging role of probiotics in neurodegenerative diseases: new hope for Parkinson's disease?

Neurodegenerative disease etiology is still unclear, but different contributing factors, such as lifestyle and genetic factors are involved. Altered components of the gut could play a key role in the gut-brain axis, which is a bidirectional system between the central nervous system and the enteric nervous system. Variations in the composition of the gut microbiota and its function between healthy people and patients have been reported for a variety of human disorders comprising metabolic, autoimmune, cancer, and, notably, neurodegenerative disorders. Diet can alter the microbiota composition, affecting the gut-brain axis function. Different nutraceutical interventions have been devoted to normalizing gut microbiome dysbiosis and to improving biological outcomes in neurological conditions, including the use of probiotics. Preclinical and clinical investigations discussed in this review strengthen the correlation between intestinal microbiota and brain and the concept that modifying the microbiome composition may improve brain neurochemistry, modulating different pathways. This review will discuss the potential use of probiotics for Parkinson's disease prevention or treatment or as adjuvant therapy, confirming that gut microbiota modulation influences different pro-survival pathways. Future investigations in Parkinson's disease should consider the role of the gut-brain axis and additional comprehension of the underlying mechanisms is extremely necessary.