MAPT and Alzheimer disease: For example, it was recently reported that prior to the formation of extracellular Aβ deposits and intracellular tau tangles in the human brain, there is an intracellular accumulation of soluble Aβ oligomers (iAβo) during AD, especially in vulnerable regions such as the entorhinal cortex and hippocampus (Welikovitch et al., 2018).