Is there a difference between anti-depressants and sugar pill (placebo)?
In case you didn't see this article or hear about the studies on antidepressants: http://www.nytimes.com/2012/04/22/magazine/the-science-and-history-of-treating-depression.html
Antidepressants are no better than placebo for treating depression. Strikingly, this is information the drug companies AND the FDA knew from the very first time studies were submitted to the government in order to approve the drugs (for sale in the United States.)
One prominent author (Irving Kirsch) says that this doesn't mean that antidepressants don't work at all; rather, it means placebo works really well for treating depression. He also points out that almost any drug (not just antidepressants) works for depression, even medications that LOWER serotonin (!) He also points out that counselling and therapy, and even St. John's Wort, do work better than placebo. But mostly, he says, placebo is very powerful medicine - another way of saying that our beliefs and thoughts powerfully influence our health.
Of course, no one has performed comparable studies on PMDD and SSRIs, but since - as the NY Times article points out - the theory of "neurotransmitters causing depression" is considered scientifically dead, it stands to reason that there is little or no benefit greater than that of placebo for this application of these drugs.
Dr. Daniel Heller
p.s. This research is not a reason to stop taking SSRIs if you feel they've helped you. And, if you decide you would like to discontinue them, it's essential to do so slowly and carefully under the guidance of a qualified health care practitioner.