MAPT and semantic dementia: (ii)Tau. Hyper-phosphorylation of tau (p-tau) can cause an accumulation of paired helical filaments of tau, known as neurofibrillary tangles (NFT), a hallmark pathology of different neurodegenerative diseases, including AD, frontotemporal dementia with parkinsonism (FTDP), and progressive supra-nuclear palsy (PSP) [79].