In bvFTD, both total tau (t-tau) and p-tau181 levels are lower than in Alzheimer’s disease (AD) (Bian et al., 2008), and there is evidence that the ratio of p-tau181 to t-tau in CSF is lower in FTLD-TDP than in FTLD-tau (Hu et al., 2013; Borroni et al., 2015). This evidence concerns the gene MAPT and Alzheimer disease.