The question being asked in this study is whether the knowledge (or belief) that one is receiving a placebo can still result in placebo effects. Or, as commonly believed, would the knowledge that one is receiving a placebo neutralize the placebo effects that might otherwise be elicited by patients who think they are receiving active, effective medication. The study design did not—and could not---answer this question.
Patients in this study were told that the placebo pills they would be given had no (pharmacologically induced) medicinal value. At the same time, they were told that these placebo treatments were effective in alleviating symptoms of irritable bowel syndrome (ISB) by eliciting significant mind-body self-healing processes. What, then, is the patient likely to think? Do patients mistakenly hear these statements as being contradictory? Do they wonder which of these statements is true? Patients suffering from a chronic disorder such as IBS—as many as 50%, or more--might be expected to choose the message that the placebo pills would have a therapeutic effect by whatever means. After all, the recruitment advertisements referred to this as “a novel mind-body management study of IBS,” emphasizing nonpharmacologic placebo effects.
Actually, this experiment did not bear directly on the widespread belief that placebo responses are neutralized by an awareness that the treatment is a placebo. Such a study would have included a group that was informed that the placebo pills had no pharmacotherapeutic effects and nothing more—as well as a group that received active medication. It turns out to be a study to determine whether the knowledge that the pills prescribed were pharmacologically inactive, could overcome the more extensively discussed therapeutic effects of these placebo pills mediated by other mind-body, self-healing processes. As it stands, then, the study did not show that one can observe placebo effects even if patients are told that the placebo pills have no medicinal effects. It showed that the power of suggestion by authority figures could override the knowledge that a placebo is pharmacologically inactive. The more elaborate descriptions that were given about the means by which the pharmacologically inactive placebo pills could influence IBS symptoms were more meaningful and persuasive to this population than the information that the pills would have no pharmacotherapeutic effects.

Robert Ader, Ph.D.
University of Rochester
School of Medicine and Dentistry
Rochester, NY 14642