BDNF and major depressive disorder: For example, a central regulator of homeostasis in the brain, the brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family of proteins that plays crucial roles in the development, maintenance, and plasticity of the CNS (Chao et al., 2006) have been demonstrated to play an important role on different psychiatric disorders associated with early-life adversity, including depression; schizophrenia, bipolar disorder and autism.