If you've had treatment for 5 or 6 years, and it's never been too successful, then that could be called Treatment Resistant Depression. I was told I had that after a year of so of failing treatment with medication. It led to the pdoc offering me ECT (shock treatment.) I declined that because I heard you lose your memory doing that.

Eventually, when the circumstances of my life improved, my mood improved. Sometimes, it's not your brain that's messed up, but the conditions of your life.