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Updated: May 16, 2026

Dynamic Digital Biomarkers of Motor and Cognitive Function in Parkinson's Disease
Published on: July 24, 2019
Unimpaired postprandial pancreatic polypeptide secretion in Parkinson's disease and REM sleep behavior disorder
Marcus M Unger1, Rolf Ekman, Anna-Karin Björklund
1Department of Neurology, Philipps-University Marburg, Marburg, Germany. marcus.unger@uks.eu
Background:
Pancreatic polypeptide is released immediately after food ingestion. The release is operated by vagal-abdominal projections and has therefore been suggested as a test for vagal nerve integrity. Pathoanatomical and clinical studies indicate vagal dysfunction in early Parkinson's disease (PD).
Methods:
We assessed the postprandial secretion of pancreatic polypeptide and motilin in healthy controls (n = 18) and patients with idiopathic rapid-eye-movement sleep behavior disorder (iRBD, n = 10), a potential premotor stage of PD, as well as in drug-naive (n = 19) and treated (n = 19) PD patients.
Results:
The postprandial pancreatic polypeptide secretion showed a physiological pattern in all groups and even an enhanced response in drug-naive PD and iRBD. Motilin concentrations correlated with pancreatic polypeptide concentrations.
Conclusions:
Postprandial pancreatic polypeptide secretion is not a suitable test for vagal nerve integrity in PD. The unimpaired pancreatic polypeptide response in iRBD and PD might be explained by partially intact vagal-abdominal projections or compensatory mechanisms substituting a defective neuronal brain-gut axis.
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