MAPT and Alzheimer disease: For example, synaptic dysfunction, which is assumed an immediate early symptom in AD, is caused by soluble Aβ oligomers (Cline et al., 2018; Li and Selkoe, 2020), and Aβ oligomers trigger the pathological cascade of AD including tau hyperphosphorylation, glial activation, and neuronal loss (Tomiyama et al., 2010; Cline et al., 2018).