While evidence has linked FTD with parkinsonism in patients to tau mutations on chromosome 17 (FTDP-17), implying that tau dysfunction alone can cause neurodegeneration (Reed et al., 2001), studies in animal models have shown that overexpression of tau can lead to cell death (Lee et al., 2001; Tanemura et al., 2001, 2002; Tatebayashi et al., 2002) and exhibit behavioral abnormalities and synaptic dysfunction without the presence of NFTs (Wittmann et al., 2001; Andorfer et al., 2003; Santacruz et al., 2005; Spires et al., 2006; Berger et al., 2007; Yoshiyama et al., 2007; Cowan et al., 2010). Here, MAPT is linked to frontotemporal dementia.