MAPT and Alzheimer disease: Indeed, the emergence of the new clinical variant of PPA, lvPPA (Gorno-Tempini et al., 2008, 2011), which is most often associated with AD neuropathology (Mesulam et al., 2008; Rabinovici et al., 2008; Grossman, 2010) (Figure 1C), and therefore suggested to be excluded from FTLD clinical trials (Knopman et al., 2008), could influence group-wise CSF tau and Aβ1−42 results.