Studies have revealed that the concentration of p‐tau in CSF accurately depicts the extent of p‐tau deposition within the AD brain [104], and in contrast to t‐tau, there is essentially no change in concentrations of certain p‐tau species in other neurological conditions like acute stroke [105] or Creutzfeldt–Jakob disease (CJD) [106], nor in other tauopathies and neurodegenerative diseases [107, 108, 109, 110, 111]. This evidence concerns the gene MAPT and Creutzfeldt Jacob disease.