MAPT and Alzheimer disease: Both Alzheimer’s disease and FTLD caused by tau (FTLD-tau) feature tau inclusions (Grundke-Iqbal et al., 1986; Hutton et al., 1998; Spillantini et al., 1998); however, other forms of presenile dementia with neurofibrillary lesions but no amyloid-β deposits have also been described (Sumi et al., 1992; Spillantini et al., 1996; Goedert, 2016), suggesting that neurofibrillary tangles frequently observed in early stages of Alzheimer’s disease pathology can occur independently of amyloid-β deposits and are associated with dementia.