BDNF and major depressive disorder: administration and/or promotion ameliorates adverse effects of stress on hippocampal serotonin, norepinephrine and brain-derived neurotrophic factor (Liang et al. 2015) and increases hippocampal and prefrontal N-acetyl-aspartate, GABA and glutamate: biomarkers that are associated with depression (Janik et al. 2016).