Objective: To examine whether changes on dopamine reuptake transporter (DAT) SPECT and transcranial sonography (TCS) correlated with Parkinson’s disease (PD) risk scores and other prodromal features in the PREDICT-PD study.

Background: DAT SPECT and TCS have been proposed as imaging markers of prodromal PD. PREDICT-PD aims to define a group at higher risk of PD using an algorithm comprised of risk factors and early non-motor features identified through systematic review (1). Subjects aged between 60-80 years at baseline have been tested annually since 2011, predominantly via the internet, using questionnaires (including the Rapid Eye Movement sleep behaviour disorder (RBD) screening questionnaire; RBDSQ), objective smell tests (University of Pennsylvania Smell Identification Test; UPSIT) and the BRAIN-tap test (which measures alternate finger taps in 30 seconds) (2).

Methods: Participants in this imaging sub-study were drawn from the wider PREDICT-PD cohort (1,323 UK residents recruited at baseline and free from known neurodegenerative disease). 46 participants that had completed all assessments (online screening questionnaire, UPSIT, RBDSQ, BRAIN-tap test, and clinical examination using the MDS-UPDRS) underwent DAT SPECT and TCS. Linear regression was used to examine associations between imaging modalities and PD risk scores, intermediate markers of prodromal PD (i.e. UPSIT and RBDSQ scores, and the number of alternate finger taps) and MDS-UPDRS scores. Risk was expressed as the log odds of PD.

Results: Striatal Binding Ratio (SBR) was associated with MDS-UPDRS motor scores (p=0.009), UPSIT scores (p=0.002), RBDSQ scores (p=0.024), tapping speed (p=0.024) and PD risk estimates (p=0.040). Using TCS, the size of nigral echogenic area was associated with MDS-UPDRS motor scores (p=0.027) and PD risk estimates (p<0.001), but not UPSIT, RBDSQ or tapping speed. Modeling PD risk estimates along with UPSIT, RBDSQ and finger tapping scores explained 26% of variation in SBR (r2 = 0.258), which was significantly more than any factor on its own.

Conclusions: SBR is associated with prodromal motor and non-motor features of PD, and TCS hyperechogenicity with risk estimates and motor scores. Combining assessments for risk markers may better predict those in the prodromal stages of PD.

References: 1. Noyce AJ et al. Meta-analysis of early nonmotor features and risk factors for Parkinson disease. Ann Neurol 2012;72:893-901

2. Noyce AJ et al. PREDICT-PD: an online approach to prospectively identify risk indicators of Parkinson’s disease. Mov Disord 2017 [In Press]

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MDS Abstracts - https://www.mdsabstracts.org/abstract/associations-of-dat-spect-and-tcs-with-prodromal-features-of-parkinsons-disease-results-in-predict-pd-participants/