I can see how a pattern of depression behaves like an addiction. It feeds on itself and you go lower and lower until something gives. Also, the work required to disrupt and break the thought patterns of depression lean on coping skills the same way addiction therapy does. The toll it takes on your life also mirrors that of addiction. Additionally, addiction and depression both interact with some of the same chemicals and systems in the brain. Maybe we need a 12 step program for depression. The serenity prayer certainly applies.