MAPT and progressive supranuclear palsy: The CSF concentrations of the fragments were not correlated to those of T-tau in primary tauopathies such as progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), suggesting that quantifying N-224 in these diseases could help in the differential diagnosis with AD, as classic tau biomarkers are often normal in non-AD dementias [9–11].