In subjects with depression, the expression of brain-derived neurotrophic factor (BDNF), which is required for neurogenesis, eventually decreases; this is associated with high GC levels, and signaling for the promotion of neurogenesis, including the phosphorylation of the signaling molecules cAMP response element-binding protein (CREB) and extracellular regulated kinase (ERK), in the hippocampus is altered, which may negatively affect the HPA axis activity. This evidence concerns the gene BDNF and depressive symptom measurement.