MAPT and Cognitive impairment: AD is associated with extracellular aggregation of amyloid-β plaques (Thal et al., 2002), intracellular accumulation of abnormally phosphorylated tau protein (Braak and Braak, 1995), progressive neuronal loss (neurodegeneration; Miller et al., 2013) and cognitive impairment (Green et al., 2000).