MAPT and Alzheimer disease: Whilst different neurodegenerative conditions are associated with disease-specific proteins such as amyloid-beta (Aβ) and hyperphosphorylated tau (tau) in AD, α-synuclein in PD, and TAR DNA-Binding Protein 43 (TDP-43) in MND, a common molecular mechanism is proposed to underlie the replication and spread of these different misfolded protein aggregates in the central nervous system (CNS) (Figure 1) [5,6].