Several endogenous peptides have anti-apoptotic and neuroprotective properties in the central nervous system, among which glycine-proline-glutamate (GPE), a natural peptide cleaved from the N-terminus of insulin-like growth factor I (IGF)-I, is a protective agent in brain injury [14] and has shown neuroprotective capabilities in experimental models of AD [15,16]. Here, IGF1 is linked to Alzheimer disease.