Table 3.

Changes in biomarkers compared to healthy control populations. As PD progresses, there is heterogeneity in the change in biomarker profiles such that some patients may increase or decrease in certain biomarkers, but others may remain stable (↑ = or ↓ =). There are competing articles about the changes seen in oligomeric aSyn over time (↓↑)

Biomarker	Prodromal PD	Early PD	Mid/late PD
CSF
t-aSyn	↓ =	↓	↑ =
o-aSyn		↑	↑↓
p-aSyn		↑	↑
Aβ42		↓	↓ =
t-tau		↓	↑ =
p-tau		↓	↑ =
Plasma
t-aSyn		↑	↑
Skin IF	+	+	+
aSyn-SAA	+	+	+

t-aSyn total alpha-synuclein, o-aSyn oligomeric alpha-synuclein, p-aSyn phosphorylated alpha-synuclein, IF immunofluorescence, aSyn-SAA alpha-synuclein seeding amplification assay