APP and early-onset autosomal dominant Alzheimer disease: Additionally, genetic background of Familial Alzheimer’s disease mice model is important, these mice are double transgenic overexpressing both mutant human amyloid precursor protein (APP) and mutant human presenilin (PS1); which results in rapid formation of amyloid plaque in brain, amyloid deposition begins at 2 months and the neuronal loss and brain dysfunction is exhibited at 4-5 months of age (79).