We first analyzed the levels of tau and phosphorylated tau in these tissue samples by Western blots developed with antibodies 77G7 (pan-tau) and PHF-1 (phospho-tau at Ser396/404) (Fig. 3a) and found hyperphosphorylation of tau at Ser396/404, which also displayed SDS- and β-ME resistant HMW-species, the common features of AD and related tauopathies, in AD2-5 and PiD3, but not in Con1-5, AD1, CBD1-3, PiD1,2, and PSP1,2 brains (Fig. 3a), suggesting that the pathology in these cases is not evenly distributed throughout the frontal cortex in tauopathies. Here, PSPC1 is linked to Alzheimer disease.