MAPT and dementia: PPO was tested as a predictor of quantitative levels of cerebrospinal fluid (CSF) β‐amyloid (1‐42) (Aβ1‐42) in those with a parental history of dementia (n = 688) and of phosphorylated tau (p‐tau) and EPAD neuropsychological examination (ENE) subscores in an amyloid positive subgroup (n = 226).