Clinical progression of Parkinson's disease in the early 21st century: Insights from the accelerating medicine partnership (AMP-PD) data

Background: Parkinson's disease (PD) therapeutic strategies have evolved since levodopa introduction in mid 1900s. To understand their impact and research gaps, this study delineated the clinical progression of PD in recent years. Methods: Using Accelerating Medicine Partnership-PD (AMP-PD) data harmonized from seven biomarker discovery studies (2010–2020), we extracted: overall [Schwab and England (S&E), PD Questionnaire (PDQ-39)]; motor [Movement Disorders Society Unified PD Rating Scale (MDS-UPDRS)-II and -III and Hoehn & Yahr (HY)]; and non-motor [MDS-UPDRS-I, University of Pennsylvania Smell Identification Test (UPSIT), Montreal Cognitive Assessment (MoCA), and Epworth Sleepiness Scale (ESS)] scores. Age at diagnosis was set as 0 years, and data were tracked for 15 subsequent years. Results: Among 3001 PD cases identified to be suitable for this study, 2838 are white, 1843 are males, with a mean age at diagnosis was 60.2 ± 10.3 years. At baseline evaluation, the disease duration was 9.9 ± 6.0 years overall, 1915 within 0–5, 541 with 6–10, 254 within 11–15, and 163 greater than 15 years. Participants largely reported independence (S&E, 5y: 86.6 ± 12.3; 10y: 78.9 ± 19.3; 15y: 78.5 ± 17.0) and good quality of life (PDQ-39, 5y: 15.5 ± 12.3; 10y: 22.1 ± 15.8; 15y: 24.3 ± 14.4). Motor scores displayed a linear progression, whereas non-motor scores plateaued ∼10–15 years. Younger onset age and female correlated with slower progression. Conclusions: Twenty-first century PD patients remain largely independent in the first decade of disease at tertiary subspecialty care and research centers. There are data gaps for those who are non-whites or longer PD duration, and sensible metrics that can gauge non-motor progression when PD is beyond 10 years.