TNF and major depressive disorder: Given that participants who received WBH in this study showed a rapid and sustained antidepressant response when compared to sham treatment [5], we hypothesized that the antidepressant effects of WBH would be associated with both immediate and longer-term anti-inflammatory effects of the intervention, measured primarily as reductions in plasma concentrations of IL-6, TNF and IL-1-beta, the inflammatory cytokines most frequently associated with MDD [13, 14].