The expression of tight junction-associated proteins such as ZO-1, claudin-5, and occludin decreased after CCH, and regulation of these proteins can rectify the CCH-induced BBB hyperpermeability, thereby improving cognitive function (Hawkins et al., 2004; Edrissi et al., 2016; Lee et al., 2017). The gene discussed is OCLN; the disease is columnar cell hyperplasia of the breast.