MAPT and tauopathy: AGD is a 4-repeat tauopathy characterized by argyrophilic grains, pretangles, granular fuzzy astrocytes and ballooned achromatic neurons in the medial temporal lobe [6, 35]; however, a subset of AGD cases shows tau pathology that extends beyond the medial temporal lobe, involving the cingulate gyrus and superior temporal gyrus, which is referred to as diffuse AGD [25].