The placebo effect describes a beneficial or positive response to an inert intervention. Its counterpart — the nocebo effect — refers to a negative reaction to an inactive treatment.
Scientists often use placebo-controlled trials to evaluate medical interventions, so understanding how and why these effects arise is important. After all, if people experience relief from their symptoms or develop side effects when they have only taken a sugar pill, this makes interpreting the results of studies more difficult.
For instance, the authors of a meta-analysisTrusted Source of trials investigating antidepressant medications concluded that “the placebo effect accounted for 68% of the effect in the drug groups.”
The importance of the placebo
The placebo response’s effect on the reliability of clinical trials is well-known. However, there is an even more important reason to study them: If an inert pill has the power to make someone feel better, we should try to harness it.
As the authors explain, scientists need to find ways of minimizing the placebo effect in clinical trials and maximizing it in the clinic.
Already, scientists have uncovered a range of factors that contribute to the placebo effect. So far, they have shown that genetics, learning and conditioning, and individual expectations of a treatment outcome play a part.
An addition to this list is personality, which was the focus of a recent review featuring in the Journal of Psychosomatic Research.