Brain‐Derived Neurotrophic Factor and Major Depression

and a leading cause of disability worldwide. While many effective antidepressant treatments are available, the neurobiology of depression, as well as the mechanism of action (MOA) of antidepressants, remains unclear. Recent investigations of brain-derived neurotrophic factor (BDNF) support its putative role in both the pathophysiology of depression and antidepressants’ MOA. Preclinical studies of depression indicate that BDNF has effects comparable to those of antidepressants. Brain levels of BDNF in animals decrease in response to stress while increases occur in response to antidepressants, electroconvulsive shock (ECS), vagus nerve stimulation (VNS), and transcranial magnetic stimulation (TMS). In addition, a growing number of clinical studies support its role as a marker of antidepressant activity.