Objective: To implement staged screening to identify people with features of prodromal Parkinson’s disease (PD).

Background: The subtle motor and non-motor symptoms that occur prior to diagnosis of PD – the prodromal stage – may be an essential time for intervention to slow disease progression before substantial neurodegeneration has occurred. Identifying large numbers of people with characteristics of prodromal PD is necessary for identifying enriched groups at particularly high risk, for biomarker development and clinical trials.

Method: PPMI Online is a web-based platform consisting of participant reported outcomes (PROs) evaluating motor function, mood, quality of life, health history, and cognition quarterly. Prodromal risk algorithms identify individuals eligible for additional assessments (e.g., olfactory testing, dopamine transporter imaging), some of whom will enroll in the in-person PPMI. The sample consisted of participants without PD who completed a screening questionnaire about prodromal features (RBD or hyposmia) or genetic risk (family history of PD), and a subset of those who completed a smell test (UPSIT) by mail. We used other online PROs to determine the prevalence of prodromal symptoms in this group.

Results: Over 7 months, 10,324 people without PD completed the screening questionnaire [Table 1]. Overall, 2,155 (21%) participants were over 60 years old and endorsed prodromal features or family history [Table 2]. Of 561 of these participants who completed an UPSIT, 48 (8.6%) were below the 8th percentile expected for age and sex. Restricting participants to those who endorsed either a diagnosis of REM sleep behavior disorder (RBD), symptoms of dream enactment behavior (DEB), or problems with sense of smell increased the proportion scoring below the 8th percentile to 19.6% (44/225). Participants with this level of hyposmia reported smaller handwriting (28% vs 11%), reduced facial expressiveness (9.8% vs 1.3%), and less frequent bowel movements.

Conclusion: A staged process beginning with online screening identifies people with various features of prodromal PD. Online questionnaires may allow for screening of large populations while reducing research costs and participant burden. Verification with UPSIT and subsequent in person imaging and clinical assessment will improve the precision and may allow for specific algorithms for different subgroups.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/parkinsons-progression-marker-initiative-ppmi-online-identifies-people-with-features-of-prodromal-parkinsons-disease-through-online-questionnaires/