Regardless of whether someone uses talk therapy or pharmacology, or a combination of the two to achieve relief from depression, ultimately, any relief they experience is the consequence of neural plasticity (also called neuroplasticity), which is essentially changes in the function of neural circuits in the brain and/or body. Brain-derived neurotrophic factor (BDNF) was discovered for its role in promoting the growth, survival, and neuroplasticity of neurons, although it has other roles as well.