MAPT and Alzheimer disease: In AD, loss of synapses and neurons is accompanied neuropathologically by amyloid deposits composed of the Amyloid beta (Aβ) peptide, and neurofibrillary tangles composed of modified versions of the tau protein (Trojanowski and Lee, 2002; Schellenberg and Montine, 2012; Sheng et al., 2012).