PET studies, and particularly tau‐PET observations, confirm that: (i) tau pathology precedes by several decades the appearance of β‐amyloid in brain aging without cognitive impairment; (ii) tau pathology may be found in some individuals suffering from cognitive impairment without concomitant β‐amyloid deposition, and; (iii) tau pathology, rather than β‐amyloid pathology, correlates with progressive cognitive decline in sAD. The gene discussed is MAPT; the disease is Mental deterioration.