A healthy gut for a healthy brain: preclinical, clinical and regulatory aspects

A large body of research has shown the presence of a complex pathway of communications between the gut and the brain. It is now recognized that, through this pathway, the microbiota can influence brain homeostasis and plasticity under normal and pathological conditions. This review aims at providing an overview of preclinical and clinical pieces of evidence supporting the possible role of gutbrain axis modulation in physiological aging, in a neurodevelopmental disorder, the autism spectrum disorders and in a substance abuse disorder, the alcohol addiction. Since the normalization of gut flora can prevent changes in the behavior, we postulate that the gut-brain axis might represent a possible target for pharmacological and dietary strategies aimed at improving not only intestinal but also mental health. The present review also reports some regulatory considerations regarding the use of probiotics, illustrating the most debated issues about the possibility of considering probiotics not only as a food supplement but also as a "full" medicinal product.