Indices of inflammation [e.g., circulating levels of cytokines (e.g., interleukin-6 (IL-6) and acute phase proteins (e.g., C-reactive protein (CRP)] are elevated in individuals with depression compared to controls [12] and inflammatory biomarkers have been linked to specific aspects of depression, such as anhedonia and negative affect [13, 14]. This evidence concerns the gene IL6 and depressive disorder.