This theory is supported by the expression of peripheral inflammatory markers in delirium, including C-reactive protein, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and IL-6 (Gool et al., 2010; Cape et al., 2014; Capri et al., 2014; Cerejeira et al., 2014). Here, TNF is linked to delirium.