A number of preclinical studies have also suggested that the brain-derived neurotrophic factor (BDNF), a well-established neurotrophin, plays an important role in the pathophysiology of numerous psychiatric disorders (Teche et al., 2013; Munkholm et al., 2014; Akyol et al., 2015) and regulates neuronal growth, survival, and function of the adult brain (Yukimasa et al., 2006; Calabrese et al., 2014). Here, BDNF is linked to psychiatric disorder.