LRRK2 and Parkinson disease: While non-statistically significant, there was a trend towards faster motor decline in participants with α-syn SAA positive LRRK2 PD compared to those with α-syn SAA negative LRRK2 PD (MDS-UPDRS III points per year: 2.39 (95% confidence interval: 1.86 – 2.92) vs. 1.76 (0.93 – 2.60); difference=0.63 (−0.29 – 1.55, p=0.18).