Imaging treatment effects in depression.

In the past years a multitude of studies has revealed alterations on a neuromolecular, structural and network level in patients with major depressive disorder within key regions of emotion and cognition processing as well as implicated neurotransmitter systems. The present review is thought to give an overview over recent developments with regard to treatment-induced changes in structural, functional and molecular neuroimaging. A number of studies could show that antidepressant treatment may lead to a partial restorage of primarily altered processes. This becomes evident in structural magnetic resonance imaging studies which point towards the reduction of volumetric differences between depressed patients and healthy controls during treatment, along with a normalization of neuronal functioning as assessed with functional magnetic resonance imaging. On a molecular level positron emission tomography studies investigating targets which are fundamentally implicated in antidepressant action such as serotonergic and dopaminergic transporters and receptors have shown to be sustainably influenced by antidepressant treatment. However, it seems that not all dysfunctional processes can be reversed by antidepressant treatment and that state and trait factors are evident not only on a behavioral but also on a neurobiological level.