In addition, the brain-derived neurotrophic factor (BDNF) hypothesis (Nestler and Carlezon, 2006; Krishnan and Nestler, 2008; Pittenger and Duman, 2008) implies that an increase in BDNF at the VT area and nucleus accumbens (NAc) may increase neurovegetative symptoms associated with depression. This evidence concerns the gene BDNF and major depressive disorder.