BDNF and major depressive disorder: Decreases of BDNF levels are accompanied by and are believed to lead to several pathologies, including neuropsychiatric disorders like anxiety-related behaviours, depression, bipolar disorder, schizophrenia and neurodegenerative disorders like Huntington's, Parkinson's and Alzheimer's diseases (reviewed in Binder and Scharfman, 2004; Angelucci et al., 2005; Duman and Monteggia, 2006).