It is also well-established that inflammation within the central nervous system (CNS) significantly contributes to the development of psychiatric diseases (Stephenson et al., 2018), whereby pro-inflammatory cytokines, such as interleukin 1 beta (IL-1β), IL-6 and tumour necrosis factor-alpha (TNF-α) are significantly raised in serum and cerebral spinal fluid (CSF) of, at least, a subgroup of patients suffering from depression (Wang and Miller, 2018; Zou et al., 2018). This evidence concerns the gene IL1B and depressive disorder.