Additionally, circulating levels of various pro-inflammatory cytokines such as interleukin 6 (IL-6) and interleukin 17A (IL-17A) have been shown to be elevated in the PTSD population (von Känel et al., 2007; Zhou et al., 2014; Imai et al., 2018; Maloley et al., 2019). Here, IL6 is linked to post-traumatic stress disorder.