How do you know that you would not have had the same repsonse if not a better one if you were given a placebo??
Oddly enough, my mother did try placebos at one point (she was a nurse, so was in to that sort of stuff). She would give me what I later found out was a small amount of milk with vanilla essence in it, and tell me it was "medicine". It worked to calm the panic somewhat, but not prevent it from occurring (and oddly enough, I'd rather it just didn't occur full-stop).
However once I hit puberty pretty much everything went out of the window (thanks hormones!). Even now I have noticed that I'm more likely to have problems during certain points in the hormone cycle.
Add to that that I've been on three different versions (paroxetine, sertraline and venlafaxine), and had very different experiences from each. If I was only experiencing the placebo effect, I'd expect to have a similar outcome from each, but that wasn't the case (Paroxetine was good, but lost efficacy. Sertraline was awesome for the OCD (stopped it dead), middling on the anxiety, and made me an emotional mess. Venlafaxine is good for the anxiety, but only passable for the OCD).
Quark! Quark! Beware the quantum duck!