Parkinson's disease (PD) is a common neurodegenerative disease that affects millions worldwide. Now, a groundbreaking clinical study has demonstrated the potential of fecal microbiota transplantation (FMT) to improve symptoms in patients with PD. Motoric symptoms, such as balance problems, stiffness, and the characteristic tremor, are the best known and almost always the reason for the eventual diagnosis. However, non-motor symptoms, such as loss of smell, constipation, and REM sleep disturbances, often develop up to 20 years before diagnosis in a large number of people with the disease. In Parkinson's disease, a protein called alpha-synuclein misfolds and clumps together. Those clumps...