Brain changes in depression.

The present review addresses major depressive disorder (MDD) and the implications of antidepressant treatment in the field of brain neuroplasticity, an effect initially considered adjacent but currently passed as central in the process of remission of MDD. Both in experimental animal studies and in human studies in subjects with mood disorders, neuroplasticity is considered the fundamental mechanism of neural defense against stress. Stress is the mediator between neurofunctional, neuroendocrine, neurobiological and neuroimmune disorders and depressive pathology of various intensities. Neurons have a high potential to adapt to the influences of internal and external factors. We are talking about neuroplasticity at different levels: structural neuroplasticity involving adult neurogenesis (such as plastic changes, dendritic reconstruction, when the morphology of the spine is affected); synaptic functional neuroplasticity and molecular and cellular mechanisms involved. These two major dimensions explain the pathophysiology of depression, as well as the convergence of the mechanisms involved in stress, major depressive decompensations, and the concept of neuroplasticity as the present target for new effective and potent antidepressant treatments.