Given previous findings that BDNF expression peaks in the hippocampus and prefrontal cortex during adolescence and gradually decreases with age, these results suggest that decreased BDNF expression and function during adolescence may be a major risk factor for the development of depression and other mood disorders, such as anxiety disorder (Figure 1; Dincheva et al., 2016). The gene discussed is BDNF; the disease is depressive disorder.