MAPT and Alzheimer disease: Among current tau PET tracers, the efficacy in assessing non-AD tau, including primary age-related tauopathy, is still unclear and could lead to underestimation of overall tau pathology.59 Future studies using a longitudinal design could help to clarify the extent to which medial temporal tau deposits due to distinct (AD and non-AD) etiologies may have differential associations with the variables analyzed in this study.