APP and neurodegenerative disease: Caspases play a significant role in the pathogenesis of different neurodegenerative diseases including AD, PD and Huntington’s disease (HD), since they are able to modify the properties of different neurotoxic proteins aggregates (amyloid precursor protein (APP), Tau, α-synuclein (α-Syn) and huntingtin (htt) through cleavage.