MAPT and early-onset autosomal dominant Alzheimer disease: As intraneural soluble amyloid-β is observed in the human brain before the appearance of extracellular amyloid-β plaques and tau phosphorylation, it is likely that there is a build-up of the soluble intraneural pool prior to the appearance of classical hallmarks of Alzheimer’s disease (Welikovitch et al., 2018).