While we don't know the exact causes, and there are complex factors in play, it is most certainly a chemical imbalance. Imagine you could take a perfect chemical "snapshot" of the brain/body when it's in a normal mood and again in depressed state. Do you seriously think there would be no difference chemically?
I've take SSRIs off & on for the last 15 years. I'm currently on them after experiencing suicidal depression this summer. (I suspect it was partially induced by taking Chantix.)
Exercise can help, but in my case it doesn't make much difference. When my latest onset hit I was (and still am) in the best shape of my life and maintaining 10% body fat. I've been doing Crossfit for the last 15 months. Very strenuous.
I've take SSRIs off & on for the last 15 years. I'm currently on them after experiencing suicidal depression this summer. (I suspect it was partially induced by taking Chantix.)
Exercise can help, but in my case it doesn't make much difference. When my latest onset hit I was (and still am) in the best shape of my life and maintaining 10% body fat. I've been doing Crossfit for the last 15 months. Very strenuous.