How scary is This?

While searching for understanding, I've been falling asleep to abstracts and am still without a saisfactory answer as to how prescriptions of SSRIs are justified.What's so wrong with this: "While tests do exist to measure serotonin levels in the central nervous system they are not practical for the purposes of diagnosing serotonin deficiency. As an alternative, it is best to look at the symptoms of serotonin deficiency and determine if you have symptoms that match." http://www.serotune.com/blogs/articles/2659862-what-are-the-symptoms-and-causes-of-serotonin-deficiency How is that a scientific approach to treatment?  How is that a good determination of the cause of symptoms?  How about this pleasant little drop of information instead? http://www.jclinpsychiatry.com/pcc/pccpdf/v04s02/v63s0403.pdf . O.K., back to SSRI's and the serotonin level theory. Does every person diagnosed with major depressive disorder get that diagnosis based on a PET scan?  Would a blood test for serotonin be an accurate reflection of levels within the brain? No, no it wouldn't. Why not? Because levels of serotonin vary in different areas of the body, as well as it's functions in those areas. If the concentration of serotonin is raised throughout the body, how will all of these other systems be affected, besides the brain? I tend to agree with this: "The serotonin theory of depression is a good illustration that if you repeat something enough times, people will come to believe it. " http://www.psychologytoday.com/blog/charting-the-depths/201007/the-serotonin-theory-depression-is-collapsing Interestingly enough, a high serotonin level in blood from the body does not indicate an absense of depression which is logical conjecture based on pharmaceutical promotion of  anti depressants. "This test may be done to diagnose carcinoid syndrome. Many patients with carcinoid syndrome have high levels of serotonin in blood and urine."http://www.nlm.nih.gov/medlineplus/ency/article/003562.htm . Hmm. I'm getting closer:"The normal range is 101-283 nanograms per milliliter (ng/mL)'" .http://www.nlm.nih.gov/medlineplus/ency/article/003562.htm Well, this measurement can't work for the serotonin theory of depression, can it? I did mention PET scan before. How could such a thing be useful for determining levels of brain chemicals? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2621104/ and then there is this:http://news.wustl.edu/news/pages/3388.aspx. Could routine PET scans become tools for scientificaly based diagnoses? Or, is it more profitable to use other less correlated testing methods? Who reaps the rewards of the rampant theory based treatment modalities? The antidepressant industry is a masterwork of marketing strategy, isn't it? Finally, a test with promise:http://www.mayoclinic.org/news2011-rst/6165.html

The scope of the application of SSRI's includes Fibromyalgia as well, which I find discomfitting,
especially when I read this: http://www.ncbi.nlm.nih.gov/pubmed/9058665
And then there is this charming information: http://www.medicinenet.com/duloxetine/article.htm
What is the difference between what 'experts believe' and what is absolutely proven through concrete measurements and definitions-in short-the scientific method executed as flawlessly as humanly possible? I don't want pharmaceutical faith healing, because no true healing comes from that approach.
So studies, or educated 'beliefs'? I just love this conclusion: http://www.ncbi.nlm.nih.gov/pubmed/11203736  Doesn't this conclusion negate the usefulness of SSRI's nicely?