Objective: The aim of the study was to assess the prevalence of prodromal PD based on the MDS research criteria in a population of patients undergoing diagnostic colonoscopies and to evaluate the relationship between these criteria as well as presence of individual risk and prodromal markers of PD and presence of colonic a-synuclein.

Background: There has been a number of studies showing presence of a-synuclein in peripheral tissues, including the colon. However, no study so far assessed the value of colonic a-synuclein as a potential biomarker of PD prospectively so far. Recently, MDS research criteria for prodromal Parkinson’s disease (PD) have been published [1]. 

Methods: We evaluated elderly patients without motor parkinsonism undergoing diagnostic colonoscopies. During the study we assessed all risk and prodromal markers of the MDS research criteria, except radiotracer imaging and genetic testing. Colonic biopsies were obtained from ascending and sigmoid colon and were stained for presence of phosphorylated a-synuclein (P-a-syn) with proteinase-K pretreatment. A subgroup of patients with clinically diagnosed PD was enrolled as well.

Results: Mean age of the 86 enrolled patients without motor parkinsonism was 62.0 ± 10.1 years, 40 were men. Additional 6 patients with clinically manifest motor PD were enrolled as well. Seven out of the 86 enrolled patients (8%) met criteria for prodromal PD. Most common risk and prodromal markers were constipation (45.3%), followed by hyposmia (37.2%) and MDS-UPDRS part III score >6 points (34.9%). P-a-syn was present in 3/6 (50%) of patients with clinically manifest PD, in 2/7 (28.6%) patients meeting and 22/78 (28.2%) patients not meeting the prodromal PD criteria. Even though there was a tendency of higher prevalence of constipation in patients with positive vs. negative P-a-syn stainings (62.5% vs 39.3%) this was not statistically significant (p=0.06). There was no significant difference between any other risk or prodromal marker between patients with positive or negative P-a-syn staning.

Conclusions: There was no statistical difference in presence of colonic P-a-syn between those who did or did not meet the MDS research criteria for prodromal PD, there was also no statistical difference between prevalence of risk or prodromal markers and presence or absence of P-a-syn.

References: [1] Berg D, Postuma R, Adler C, Bloem B, Chan P, Dubois B, Gasser T, Goetz CG, Halliday G, Joseph L, Lang AE, Liepelt-Scarfone I, Litvan I, Marek K, Obeso J, Oertel W, Olanow CW, Poewe W, Stern M, & Deuschl G. (2015) MDS research criteria for prodromal Parkinson’s disease. Mov Disord, 30, 1600-1609.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/relationship-between-the-presence-of-colonic-a-synuclein-and-mds-research-criteria-for-prodromal-pd-in-patients-without-manifest-motor-parkinsonism-parcas-study/