Gut-derived Neuropeptides in Cerebrospinal Fluid of Patients With Parkinson's Disease and Healthy Controls

In previous work, the investigators analyzed the concentration of gut-derived peptides (ghrelin, pancreatic polypeptide \[PP\]) in serum of patients with Parkinson's disease (PD). The investigators have shown that the secretion pattern differs between PD patients and controls. Beside ghrelin and pancreatic polypeptide other gut-derived peptides (e.g. Glucagon-like-Peptide 1\[GLP-1\], Amylin, etc.) might be relevant for PD as well. The rational to investigate gut-derived peptides in the neurological disorder Parkinson's disease (PD) is based on the following considerations: * Receptors for gut-derived peptides are expressed in Central Nervous System (CNS) structures that are affected by the neurodegenerative process underlying Parkinson's disease * Gut-derived peptides are involved in the modulation of higher brain functions (mood, cognition, reward-related behaviour) that are frequently altered in Parkinson's disease. * The secretion of gut peptides is (co-)regulated by the vagal nerve that is dysfunctional in Parkinson's disease. * Certain gut-derived peptides (ghrelin, GLP-1) stimulate neurogenesis and might be able to prevent cell death in neurodegenerative disorders, including Parkinson's disease. Objective: Collection of CSF and serum samples in a standardized way in order to quantitatively measure the concentration of gut-derived peptides (ghrelin, leptin, glucose-dependent insulinotropic peptide \[GIP\], GLP-1, amylin, PP, peptide YY \[PYY\], and insulin). Scientific questions: 1. Do CSF (and serum) concentrations of these gut peptides differ between PD patients and controls? 2. Do CSF (and serum) concentrations of the investigated peptides correlate with clinical and / or epidemiological characteristics of the investigated subjects (age, gender, BMI, disease duration, severity of motor impairments, presence of non-motor symptoms, co-morbidities, medication, etc.)?