MAPT and Alzheimer disease: Although previous studies assumed that soluble P‐tau measures reflected tau pathology in AD (Jack et al, 2018), direct correlations between soluble P‐tau and neuropathology or PET measures of tau typically only found moderate correlations (Buerger et al, 2006, 2007; Mattsson et al, 2017b; La Joie et al, 2018).