Our findings showed an up-regulation of the NRG1 in the MDD patients compared to HCs in both blood and saliva samples which per several mice models studies showed that increases in the Nrg1 expression resulted in deficits in the response to a stimulus, hyper-agitation and perturbation in the working memory (Deakin et al., 2009, 2012; Kato et al., 2010; Yin et al., 2013). This evidence concerns the gene NRG1 and major depressive disorder.