Dopamine reuptake transporter–single‐photon emission computed tomography and transcranial sonography as imaging markers of prediagnostic Parkinson's disease

ABSTRACT Objective: The objective of this study was to examine whether prediagnostic features of Parkinson's disease (PD) were associated with changes in dopamine reuptake transporter–single‐photon emission computed tomography and transcranial sonography. Methods: Prediagnostic features of PD (risk estimates, University of Pennsylvania Smell Identification Test, Rapid Eye Movement Sleep Behavior Disorder Screening Questionnaire, and finger‐tapping scores) were assessed in a large cohort of older U.K. residents. A total of 46 participants were included in analyses of prediagnostic features and MDS‐UPDRS scores with the striatal binding ratio on dopamine reuptake transporter–single‐photon emission computed tomography and nigral hyperechogenicity on transcranial sonography. Results: The striatal binding ratio was associated with PD risk estimates (P = .040), University of Pennsylvania Smell Identification Test (P = .002), Rapid Eye Movement Sleep Behavior Disorder Screening Questionnaire scores (P = .024), tapping speed (P = .024), and MDS‐UPDRS motor scores (P = .009). Remotely collected assessments explained 26% of variation in the striatal binding ratio. The inclusion of MDS‐UPDRS motor scores did not explain additional variance. The size of the nigral echogenic area on transcranial sonography was associated with risk estimates (P