MAPT and Alzheimer disease: Moreover, the histopathological features of AD are senile plaques composed of amyloid beta (Aβ) fibrils and neurofibrillary tangles composed of microtubule-associated protein tau, combined with massive cholinergic neuronal loss, mainly in the hippocampus and association regions of neocortex (Hardy, 2006; Ballatore et al., 2007).