APP and Alzheimer disease: Two main pathological hallmarks of AD are the presence of extracellular aggregates of amyloid-beta peptide (Aβ) derived from the transmembrane amyloid precursor protein (APP) and the presence of neurofibrillary protein tangles, which might be composed of hyperphosphorylated tau, withinside the temporal lobe and different cortical areas in the brain which might be related to the death of neuronal cells and synaptic depletion (21).