APP and Alzheimer disease: For many years it has been known that Aβ peptide, one of the main players in AD pathology derived by the β- and γ-secretase cleavage of the amyloid precursor protein (APP), can induce morphological and functional alterations to synapses and synaptic plasticity (Selkoe, 2002; Coleman and Yao, 2003; Almeida et al., 2005).