Reverse Placebo Effect?

[tonygraham]

Is there such a thing as a "reverse" placebo effect? That is, if a patient were to take a clinically-proven drug for a condition, but they were convinced that it would be ineffective, would its effectiveness actually be lessened? I'm particularly interested to find out if anyone knows of any studies on this.
Cheers

[RCNelson]

What you're asking about is very close to (but not quite) the nocebo (http://skepdic.com/nocebo.html) effect.