This highlights a strategic regional analysis in the future, and a handful of other ideas, such as treating OI as a categorical variable (e.g., anosmia, normosmia), using t-tau/Aβ42 or p-tau/Aβ42, focusing on the APOE ε4 allele carriers, and most importantly measuring by PET tau imaging. This evidence concerns the gene APOE and Anosmia.