MAPT and Alzheimer disease: Further investigations using amyloid-PET or tau-PET would be useful to verify our results on the prevalence of pathological AD-related burden across patient groups—which we evaluated indirectly via the CSF p-tau/Aβ42 ratio—and to assess any causal connections between the alteration of Aβ42, Aβ40, and p-tau in the CSF and parenchymal amyloid and tau deposition.