BDNF and depressive disorder: In this article, the role of BDNF in the pathogenesis of a series of CNS diseases (including brain injury after stroke, depression, anxiety disorder, and neurodegenerative diseases, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and cerebellar ataxia) was reviewed (Figure 1), and the current status of research in the clinical application of BDNF and proposed future research directions are discussed.