APP and neurodegenerative disease: In the context of neurodegenerative disease, Forlenza et al. (2000) demonstrated that glycogen synthase kinase-3 β (GSK-3β)-mediated phosphorylation of tau is reduced in neurons treated with CCh, and Qiu et al. (2003) showed that CCh treatment is sufficient to reduce amyloidogenic processing of amyloid precursor protein (APP) in hippocampal slices.