Considering the significant induction of permeability by Aβ species in the in vitro BBB model, we further determined the effects of Aβ in vivo with APP/PS1 mice, a transgenic AD model using mice of two different ages (2 months to represent young mice before the onset of AD and 12 months to represent aged mice with the onset of AD). The gene discussed is APP; the disease is Alzheimer disease.