One of the most exciting breakthroughs in the AD field has been the recent development of blood tau phosphorylated at site 181 (p‐tau181) as a biomarker for AD (Tatebe et al, 2017; Mielke et al, 2018; Karikari et al, 2020; Thijssen et al, 2020; Janelidze et al, 2020a). This evidence concerns the gene MAPT and Alzheimer disease.