The transcription factor cAMP response element-binding protein (CREB) and one of its target genes, brain-derived neurotrophic factor (BDNF) are critically involved in the concept of altered neuroplasticity in MDD (Carlezon et al., 2005; Blendy, 2006; Castren and Hen, 2013; Levy et al., 2018; Umemori et al., 2018; Xiao et al., 2018; Castren and Monteggia, 2021). Here, BDNF is linked to major depressive disorder.