A study investigating Interleukin-6 (IL-6), Interleukin-8 (IL-8), and Interleukin-6 Receptor (IL-6R) genetic variations and delirium, found no polymorphisms associated with delirium (Marcantonio et al., 2006; van Munster et al., 2011). This evidence concerns the gene IL6 and delirium.