MAPT and Parkinson disease: We previously detected increased plasma levels of amyloid beta 42 (Aβ42), tau, and α-synuclein in patients with Alzheimer’s disease (AD) and PD compared to controls, using an ultra-sensitive immunoassay with immunomagnetic reduction method (IMR) (Yang et al., 2011; Chiu et al., 2014; Lin et al., 2017).