RecruitingClinical trialParkinson Progression Marker Initiative Online (PPMI Online)Parkinson Progression Marker Initiative Online (PPMI Online) is an observational study collecting participant reported information from people with and without Parkinson's disease (PD), for the goal of better understanding risk and predictive factors for PD. PPMI Online is part of the broader Parkinson Progression Marker Initiative aimed at identifying markers of disease progression for use in clinical trials of therapies to reduce progression of PD disability.