MAPT and Schnyder corneal dystrophy: To confirm that hypothesis, we postulate that longitudinal studies to analyze the transition from a non-demented stage to SCD and MCI stages should include along with molecular biomarkers (i.e., beta-amyloid and tau) the measurement of salivary cortisol, as proposed by Ho et al. (2020) to confirm, or not, that the order of events prior to development of AD is that indicated in Figure 1.