APP and Alzheimer disease: Some major pathologic features of AD have been identified, including the deposition of cerebrovascular amyloid‐beta (Abeta),1 the dysfunction of endothelial cell,2 the degeneration of cerebrovascular and neurons3 and the disruption of blood‐brain barrier (BBB).4, 5 The dysfunction of BBB may lead to impaired Abeta clearance and then an abnormal accumulation of Abeta plaques in various brain tissues, as well as the formation of pathological blood vessels.