Placebo Effect Works Both Ways.

A study quoted in Science Daily found beliefs about pain levels appear to override effects of potent pain-relieving drug.

‘Doctors shouldn’t underestimate the significant influence that patients’ negative expectations can have on outcome,’ says Professor Irene Tracey of the Centre for Functional Magnetic Resonance Imaging of the Brain at Oxford University, who led the research. For example, people with chronic pain will often have seen many doctors and tried many drugs that haven’t worked for them. They come to see the clinician with all this negative experience, not expecting to receive anything that will work for them. Doctors have almost got to work on that first before any drug will have an effect on their pain.’

The experiment done on them showed the volunteers really did experience different levels of pain when their expectations were changed, although the administration of pain relief remained constant.

Professor Tracey says there may also be lessons for the design of clinical trials. These are often carried out by comparing a candidate drug against a dummy pill to see if there is any effect of a drug above and beyond that of the placebo.’We should control for the effect of people’s expectations on the results of any clinical trial. At the very least we should make sure we minimize any negative expectations to make sure we’re not masking true efficacy in a trial drug.’