Abstract: Parkinson’s disease (PD) is the second most common neurodegenerative disease in the world and is increasing in prevalence. However, with multiple known risk factors and shortcomings in understanding the multifaceted aspects of this disease, there are as yet no cures and no established disease-modifying interventions. Historically, insights on pathogenesis have primarily come from autopsy studies, and one concern is that the pathological diagnosis does not always correspond to the clinical diagnosis (Hughes et al., 1992). This greatly limits our ability to investigate critical aspects of how the disease forms and progresses during life. In turn, this affects multiple aspects of care and research, including not only diagnosis, but appropriate subtyping that would be clinically meaningful, stratification for clinical trials, and providing optimal outcome measures for target engagement and treatment efficacy.