APP and Alzheimer disease: In various Drosophila AD models, the flies exhibit well-defined neurodegeneration phenotypes, such as synaptic and neuroanatomical defects, reduced locomotion, shorter lifespans, by introducing key amyloidogenic stages in neurons, including the initial full-length human APP695 (APP) 56, the β-cleavage of APP (β-APP, by co-expressing APP695 with β-secretase BACE1) 57, and Aβ42 58, 59.