MAPT and prion disease: Diseases such as Alzheimer's disease, Huntington's disease, Parkinson's disease and prion diseases are known to spread along neuroanatomical pathways, in a prion‐like manner [2, 3], but the relationship between pathology in different neuroanatomical regions has usually been examined at the level of deposition of intracellular (tau, α‐synuclein) or extracellular (Aβ and PrPSc) proteins [4, 5, 6].