MAPT and Alzheimer disease: Despite the already reported interaction between Aβ and tau pathologies (Shimada, 2017, Zhang, 2021) and much effort devoted to investigating the distinct association of each AD pathology and neurodegeneration (Harrison, 2021, Batzu, 2020), most existing studies failed to control the effect of one pathology when investigating the effect of the other pathology on neurodegeneration.