Table 1. Demographic details of the cohort of 189 patients with PD and 91 healthy control subjects.

	Median age (Years)	Mean Age (Years)	Disease duration (years)	[total α-syn] (ng/ml)	[pS-α-syn] (ng/ml)
PD (n = 189)	62	61.9 ± 9.7	5.10 ± 4.11	1777.1 ± 3609.6	756.8 ± 2419.9
Controls (n = 91)	66	65.3 ± 9.0	N/A	1221.5 ± 2233.1	143.4 ± 531.8

The mean values for total α-syn and phosphorylated α-syn (pS-α-syn) in blood plasma are based on the first measurement taken from the patients with PD, whilst only a single blood sample was available from the healthy controls. Disease duration refers to number of years following initial symptoms, at the time of first blood sample.