Five theories of the mechanism of depression

The neurobiology of mood disorders has been already for decades the subject of intensive experimental and clinical research. Several theories have been developed to explain the genesis of these disorders. We believe that the different mechanisms implicated by these theories are not independent from one another. Therefore, we will try to describe, how these different theories are interrelated. This will bring us finally to a model how two different brain structures induce low mood. We believe that a dysfunctioning of two different cortical-subcortical circuits is involved in major depressive disorders. The five theories of mood disorders give the mechanisms of how these circuits are affected by genetic and environmental circumstances.