Placebos can work both ways

LONDON - Poor expectations of treatment can override all the effect of a potent pain-relieving drug, a brain imaging study has shown.

Conversely, positive expectations of treatment doubles the natural physiological or biochemical effect of the opioid (world’s oldest known) drugs among healthy volunteers.

The study of the placebo effect and its opposite — the nocebo effect — appears in the journal Science Translational Medicine.

The findings suggest that doctors may need to consider dealing with patients’ beliefs about the effectiveness of any treatment, according to an Oxford University statement.

“Doctors shouldn’t underestimate the significant influence that patients’ negative expectations can have on outcome,” says Irene Tracey of the Centre for Functional Magnetic Resonance Imaging, 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. Doctors have almost got to work on that first before any drug will have an effect on their pain.

The placebo effect describes the improvements seen when patients — unknowingly — are given dummy pills or sham treatments but believe it will do them good.

Previous studies have investigated the basis of the placebo effect, when using sugar pills or saline injections for example, and confirmed it can elicit a real response.

This new research goes a step further by examining how manipulating participants’ expectations can influence their response to an active drug.