More specifically, PTSD has been consistently associated with elevated levels of pro-inflammatory markers like C reactive protein (CRP) and pro-inflammatory plasma cytokines, including interleukins (IL)-1 and IL-6 (96, 97), and recent studies have demonstrated that activity of ventral striatum in response to reward is negatively correlated with circulating concentrations of IL-6 and CRP (98). Here, IL6 is linked to post-traumatic stress disorder.