I don't understand why people are saying there are no such things as chemical imbalances. Certainly, we know that Parkinson's Disease is due to a lack of Dopamine (the inability to make it) because the area of the brain that makes Dopamine is almost non-existent in Parkinson's Disease when you look at it at autopsy. We know that their symptoms improve by replacing the Dopamine with medications. Yes, these medications have side effects, as do ALL medications. And the decision to take them must be a consideration of risks versus benefits.  
 
We don't actually "measure" insulin in people, either, but we know there is a deficiency in diabetics because we look at their symptoms and test for the effects of insulin (blood sugar), and we know they improve when you give them insulin. A lot of medical science is not based on actual measurement of deficiencies, because there is a limit to what our tests can do, but by making reasonable inferences of cause and effect with medication trials. 
 
So, if we know there can be a deficiency in neurotransmitters (like Dopamine) in certain patients, why is it hard to infer that there could be deficiencies in other neurotransmitters as well....deficiencies that cause depression and other psychiatric conditions? We are still learning about depression. ( And we are behind in that research because it is so much more prevalent in women than men, that doctors for many years just thought it was just "crazy women" acting out and they didn't take it seriously. We were supposed to "snap" out of it. A little "deja vue", Tom Cruise?) 
 
If a doctor diagnoses depression, prescribes a certain medication and it works, then there is at least some evidence that it had balanced the very neurotransmitters that the medication affects. There are going to be side effects, yes, and if the side effects are worse than the original problem, then you need to decide if it's worth it. Personally, I deal with depression. Taking anti-depressants got the suicide thoughts out of my head and gave my children a mother again and my husband a happy wife. Without the medication, I COULDN'T exercise or eat right. Now that I'm exercising and eating right, I only need a small dose of the medication. Without the meds, I would be dead. 
 
I don't know why people in our society are so extreme. There are very few things in life that are "never" or "always". Are we overmedicating America? Yes. Are there instances where medication can be life-saving? Yes. I'm happy to even be here to read the posts about why I shouldn't take medication. Ironic, huh? 
 
Tom Cruise said to Matt Lauer "You don't know the history of psychiatry. I do." Well, he doesn't know what it's like to have post-partum depression. I do. I guess that makes my opinion just as valid as his. And remember, people, his knowledge of psychiatry is that which is taught in the writings of L. Ron Hubbard. The creator of Scientology, the man who said psychiatry is evil, who criticized taking any medication, died with large amounts of anti-psychotics in his body. Go figure.