An animal model (e.g., mouse) and method of use, and cell culture assay method, for characterizing or screening a test compound for its effect on late onset Alzheimer's disease (LOAD). The test compound may be used as a therapeutic agent for treatment of Alzheimer's disease (AD). The AD animal model may be haploinsufficient for Shugoshin 1 (Sgo1) gene, or may comprise a genetic modification enabling modulation of Sgo1 expression in the brain of the animal when exposed to an Sgo1 expression-modulating compound, such as tamoxifen. After the test compound is administered to the animal model, the presence or amount of an AD biomarker is assessed or measured.