Warning on my point of view: I HATE "chemical imbalance"!

That's because I think that no one actually knows that there is such a thing and yet it continues to circulate as though it means something. The fact that SOMETIMES medications help no more means that there is a chemical imbalance than a headache means there is a lack of aspirin in the brain.

I think brain "circuits" or organizations of neurons get "trained" or altered by experience, so that they can come to reinforce something like a depression, for instance. It becomes something almost permanent. BUT it can be reversed by therapy (retraining), given enough skill by a therapist, enough understanding of brain mechanisms, and enough time!

I also think that medications might speed the process, given enough comprehension of what they do, and specific-acting enough medications. I don't think we are there now.