Matt --the condition depression in science is so very complex . There is no one explanation for the cause of depression. Thats why there is no single effective treatment for all.The frontal and temporal lobes of the forebrain are responsible for the thought assoc with depression --from there it get complex with limbic system ---as we spoke of before. I said it before its more about the wiring of the brain and how signals are sent --this is where it gets complicated. People known damage to amygdala have been studied to show autuism,phobias,anxiety and depression. It more from a neuro transmitter imbalance. Thats why not one drug works for all or one therapy--sometimes its combo of meds and cognotive therapy ..etc.