If the investigators can detect specific differences of bacterial communities between PD patients and controls this may point to a role of bacteria as a cause of PD. Since there are many ways to influence bacterial communities pharmacologically (antibiotics, probiotics) it will be possible to investigate whether these therapies could alleviate or even reverse PD symptoms. Furthermore, the investigators would be able to use these differences as a biomarker which would enable us to develop a quick screening test for bacterial samples that may reveal whether a person has PD or not.