Hence, the current study aims to examine (a) whether delirium severity in post-surgery patients with hip fracture is predicted by disturbances of the gut epithelial and the BBB as measured by using IgA/IgG responses to antigens and self-epitopes including LPS, LBP, CDT, zonulin, occludin, claudin-5, claudin-6, S100B, β-catenin, actin, P. gingivalis and H. pylori; and (b) whether these IgA/IgG responses are associated with the IRS response in post-surgery older adults. This evidence concerns the gene CLDN5 and delirium.