OCLN and Alzheimer disease: The BBB is a metabolic barrier that regulates materials exchange between the blood and CNS,33 which is of great significance to maintain brain homeostasis and its normal function.34, 35 TJs are comprised of the ZOs, occludin as well as claudins, which are considered the basic components responsible for proper function and integrity of BBB.36 Our research has displayed that MEM restored BBB permeability in AD microenvironment by up‐regulating the expression of TJ‐related proteins.