The gastrointestinal tract is inhabited by trillions of micro-organisms that form the gut microbiome, which serves various functions that can influence neurological pathways. It can release metabolites that could affect the nervous system. The bidirectional communication between the intestine and the central nervous system is known as the gut-brain axis. This communication can be impacted by the microbiota in various direct and indirect ways. There has been a suggested connection between the microbiome and many neurological disorders, including epilepsy, Alzheimer's disease, Parkinson's disease and multiple sclerosis. This has been explored in human and animal studies. While no microbial biomarkers have been identified yet, alterations in several taxa have been suggested to be associated with disease states. The potential of the microbiome to modulate neurological function has sparked multiple clinical trials using gut-altering treatments, some with positive preliminary results.