APOE and Alzheimer disease: While initial studies suggested that CSF pTau protein correlates with neocortical neurofibrillary pathology in severely demented AD patients and may serve as in vivo surrogate marker of tangle tau pathology in AD [125], other recent studies showed no association of CSF biomarkers (Aβ-42, t- and pTau) with APOE ɛ4, plaque and tangle burden in autopsy-confirmed AD [160, 161].