APOE and Mental deterioration: Numerous in vitro and in vivo studies showed that mature amyloid deposition and the associated cognitive decline is strongly stimulated by apoE and ACT in a dose-dependent and isoform-specific manner, with apoE4 being the strongest promoter of Aβ polymerization and apoE2 being an inhibitor, paralleling the effect of these two isoforms in humans [27–38].