SOD1 and Parkinson disease: Importantly, deficits in the glutathione/GPx system (Zeevalk, Razmpour, & Bernard, 2008) and in SOD1 protein (Trist et al., 2017) are also a feature of incidental Lewy body disease (ILBD), a pathologically defined disease state thought to represent preclinical PD (DelleDonne et al., 2008), indicating that these events occur during early‐stage PD prior to neuronal loss, and may play a causative role in PD etiology.