TJP1 and Brain atrophy: BBB permeability, which is associated with brain atrophy, is regulated by tight junction proteins in brain endothelial cells.[26, 35] Therefore, the expression and function of brain endothelial tight junction proteins, including occludin, claudins, and members of the membrane‐associated guanylate kinase protein family such as ZO‐1, are often used as metrics to assess BBB integrity.