APP and Alzheimer disease: The neuropathological hallmarks that characterise AD include (i) synaptic loss, which correlates with cognitive decline; (ii) aggregates of amyloid-β peptides (Aβ) generated by cleavage of the Amyloid Precursor Protein (APP); (iii) neurofibrillary tangles (NFTs) comprised of hyperphosphorylated tau protein, and (iv) gliosis and neuroinflammation [3-7].