Moreover, while numerous studies have suggested a decrease in hippocampal neurogenesis associated with depression (Ekdahl et al., 2003; Kempermann et al., 2008; Boldrini et al., 2009) and furthermore that inflammation and specifically IL-1β has the capacity to mediate this (Goshen et al., 2008; Koo and Duman, 2008; Spulber et al., 2008; Kohman and Rhodes, 2013), the mechanism(s) of action remain to be elucidated. Here, IL1B is linked to depressive disorder.