MAPT and hippocampal atrophy: Tau protein accumulations have been seen as a likely cause for hippocampal atrophy, with early tau pathology appearing specifically in the medial temporal lobe (MTL), diffusing throughout the hippocampus early in the disease process, starting from strata radiatum and oriens of CA1.22,23 Moreover, tau progression is associated with memory decline, a prime clinical indicator of Alzheimer's disease progression.64,65 This association is thought to be mediated by the atrophy of specific MTL structures while downstream of amyloid-β pathological processes.66,67