The cause of Parkinson's disease (PD) is unknown and a reliable biomarker to identify PD patients as early as possible is urgently needed. Nerve cells near the nose and in the gut become first affected in PD and patients frequently suffer from loss of smell and constipation. The nose and gut harbor very high amounts of bacteria that influence our body functions in many ways, even in the brain. The investigators are examining a possible role of bacteria of the nose and gut in the pathogenesis of PD. This may lead to a better understanding of what PD causes and may open new possibilities for diagnosis and treatment.

The investigators will recruit 100 PD patients and 100 control subjects. The investigators will characterize all subjects carefully with respect to clinical symptoms. The investigators will collect bacterial samples from the nose, mouth and stool of these subjects. Using modern genomic techniques the investigators will read out the genetic code of all bacteria contained in these samples and will be able to identify which species of bacteria are present in the samples. Using complex cluster computing the investigators will compare the pattern of bacterial species between PD patients and controls and look for specific abnormalities in PD patients.

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.

By doing this study the investigators will learn whether bacteria play a role in the development of PD and whether the investigators can use them as a biomarker or therapeutic target. So hopefully the investigators will be able in the future to better understand what causes PD, how the investigators can diagnose it as early as possible and how to cure patients from PD.

Inclusion Criteria:

• over 50 years of age

Exclusion Criteria:

• Active smoking
• relevant gastrointestinal or ENT disease

Hospital patients in- and outpatient From the community