Research has shown that the concentrations of inflammatory biomarkers—including soluble interleukin-2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-12, and IL-18—are significantly higher in the bloodstream of individuals with depression than in those without, underscoring the critical role of inflammatory processes in this condition (5). Here, IL18 is linked to major depressive disorder.