For example, psychological stress has been associated with increased production of proinflammatory cytokines including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1Ra), and IFN-γ, coupled with decreased production of anti-inflammatory cytokines including interleukin-10 (IL-10) and interleukin-4 (IL-4), with higher anxiety responses associated with significantly greater IFN-γ (Maes et al. 1998). This evidence concerns the gene TNF and Anxiety.