Recent advancements have highlighted the potential of plasma p-tau181 levels as a non-invasive biomarker for AD (Janelidze et al., 2020; Palmqvist et al., 2021), although it is unclear whether the observed p-tau181 levels reflect tau deposition in the EC because plasma p-tau181 levels are not only related to tau positron emission tomography (PET) but also to amyloid PET. Here, MAPT is linked to Alzheimer disease.