I may risk starting another war of words that started when I last posted on this topic. That post was titled Depression is not a Disease which deeply disturbed some people and started a heated discussion.
Within the comments was a discussion of the “chemical imbalance” theory which in my opinion is a load of crap. At the time I was busy, or not feeling well, or something and I did not spend much time refuting or proving my stance.
Today I came across a blog that takes on the subject very well. The author of The Healthy Skeptic is a far better academic than I and so I will simply send you over there to read his post on the subject.
The blog looks like it most likely deserves a good dig into the archives as well.