This was presented as an important biomarker in categorizing aging subjects by Cole in 2017 [5] and has since been investigated as a biomarker for different forms of dementia [6], where it seems particularly promising for Alzheimers (the difference in brain age and chronological age was well correlated to severity as measured by tau-protein-binding tracer positron emission tomography (tau-PET) within groups with minor cognitive impairment (MCI) and Alzheimer’s disease (AD)) [7]. Here, MAPT is linked to Alzheimer disease.