Inflammatory biomarkers such as interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) were elevated in patients with depression who were free from any physical illness (Zunszain et al., 2013; Alcocer-Gómez et al., 2014). Here, IL6 is linked to depressive disorder.