Synuclein assays have been recently shown to detect prodromal and clinically manifest Lewy body disease in cerebrospinal fluid (Iranzo et al., 2021), skin punch samples (Mammana et al., 2021), and recently in blood (Kluge et al., 2022): disease-specific synuclein assays may therefore offer a method of reliably differentiating MCI-LB from MCI-AD, when more clinically accessible (i.e. blood-based) biomarkers are available. Here, SNCA is linked to Alzheimer disease.