I went through four years of treatment on a variety of antidepressants. At first they seemed like a miracle. I felt "normal" for the first time in years. But after 6 six months or so the positive effect started to fade out, and the response from the Dr was to add more chemicals to the mix in order to find the right "balance". After 4 years and about 50 different chemical cocktails I made the decision on my own to get off the chemicals completely. It has been 9 years and I wouldn't touch any of that stuff with a 10 foot pole.
IMO these chemicals might work to "kick start" someone out of a chronic depression but something else is needed to effect a long term cure. For me the real cure has been strict attention to diet, exercise, and other health matters, along with exploration of psychological issues related to my past in an N-ish household.
My brother took a different path and has been taking antidepressants for 14 years. He's 80 pounds overweight, has no energy, barely functions in an entry level job. Yet he swears the antidepressants are worthwhile. I remember a time he wasn't so lethargic, so I have a hard time believing he has been "cured" by these chemicals.
I read a new theory recently about depression and the neuro chemicals in the brain which fits well with my own experience. These researchers believe the problem in depression isn't so much in the chemicals themselves (e.g. serotonin, dopamine, e.t.c..)but the way emotions are regulated by the individual. These emotions are expressed physically, but, not ultimately caused by, a certain balance of chemicals. Unlike the non-depressed, people prone to depression don't bounce back from the depressing experiences which everybody experiences everyday. And it might be a learned response. Antidepressant treatment might temporarily kick the depressed into a different chemical balance and different emotional state, but problems in the regulatory system are not addressed. So the learned responses and depressed states tend to come back.
So did some of us learn to become chronically depressed in our N-ish environments? It sure seems to fit with my experience. I don't believe I was depressed in my early years. But by the time I made a physical escape from my FOO in my late teens/early twenties I was a basket case. It certainly didn't help that I was "self medicating" with alcohol, tobacco, massive amounts of caffeine and so on. It wasn't until I gave up on these substances that things started to really improve.
Peter Breggin has written a couple of interesting books on the subject. One is titled "Talking Back to Prozac" which is his response to the the popular "Listening to Prozac". It's seems to me a good idea to investigate both sides of the issue before committing to a long term course of chemical treatment.