I feel that this is exactly what it is. In fact, I've got a two year old journal entry detailing a theory very close to this, that I wrote in the depths of a scorching case of depression.

My depression was preceded by several months of extreme psychological stress and was, in my belief, a result of that.

After getting rid of the source of the stress, and 18 months of anti-depressant medication, I am now much better.