We examined serum levels of the antibody/antibodies bound by the PD2 peptoid in two groups—“Normal Control (NC)” who remained cognitively (defined by the Montreal Cognitive Assessment) and motorically normal over an ~ 5 years period, and “PD” who were recently diagnosed with PD and had evidence from DaTscan imaging of degeneration of the nigrostriatal dopamine system. Here, PAF1 is linked to Parkinson disease.