In contrast to Aβ where conflicting evidence is available in terms of Aβ levels, P-tau has been steadily found to be raised in AD patients (Zetterberg et al., 2013, Tatebe et al., 2017, Janelidze et al., 2020, Suárez-Calvet et al., 2020, Thijssen et al., 2020, Hansson et al., 2021). This evidence concerns the gene MAPT and Alzheimer disease.