Prevalence of Prodromal Parkinson's Disease as Defined by MDS Research Criteria among Elderly Patients Undergoing Colonoscopy.

Background: Gastrointestinal symptoms are a well-recognized and common premotor feature of Parkinson's disease (PD). Moreover, multiple studies have assessed the value of colonic alpha-synuclein as a potential marker of prodromal PD. Recently, the International Parkinson and Movement Disorders Society (MDS) defined research criteria for prodromal PD. Objective: The aim of our study was to test the MDS research criteria in patients undergoing diagnostic colonoscopies as potential candidates for inclusion in prospective trials evaluating colonic biopsies as a potential biomarker of prodromal PD. Methods: We evaluated elderly patients without manifest parkinsonism undergoing diagnostic colonoscopies. During the study we assessed all risks and prodromal markers of the MDS research criteria, excluding radiotracer imaging and genetic testing. Results: The mean age of the 100 enrolled patients was 61.6 +/- 9.7 years; 42 were men. The most common prodromal marker in our cohort was constipation (40%), followed by MDS-UPDRS part III scores of >6 points, excluding action tremor items (39%) and hyposmia (37%). Substantia nigra hyperechogenicity was identified in 9%, and polysomnography confirmed REM sleep behavior disorder in 2% of the patients. Five of the 100 enrolled patients (5%) fulfilled the criteria for probable prodromal PD, while another 3 patients met the 50% probability threshold. Conclusions: Our findings suggest, that the prevalence of prodromal PD in patients undergoing diagnostic colonoscopies may be higher compared to the general elderly population, although this should be confirmed in further studies including also matched controls not undergoing colonoscopy. The real prevalence of prodromal PD in this cohort will have to be confirmed in longitudinal follow-up. Patients undergoing diagnostic colonoscopies may be good candidates for multistep screening and inclusion in prospective trials.