Placebo Outperforms Drug in Oxford Study (PsychCentral):
Positive expectations of a treatment may be more powerful than the drug itself when it comes to getting well. According to a brain imaging study at Oxford University, volunteers who believed their medication would help actually doubled the natural physiological or biochemical effects of an opioid drug. On the other hand, it was found that negative expectations could actually override the effects of the powerful pain-relieving drug.