We frequently write about placebo effects here on Science-Based Medicine. The reason is simple. They are an important topic in medicine and, at least as importantly, understanding placebo effects is critical to understanding the exaggerated claims of advocates of “complementary and alternative medicine” (CAM), now more frequently called “integrative medicine” (i.e., integrating pseudoscience with science). Over the years, I (and, of course, others) have documented how CAM advocates have consistently moved the goalposts with respect to the efficacy of their pseudoscientific interventions. As larger and better-designed clinical trials have been done demonstrating that various CAM therapies without a basis in science—I’m distinguishing these from science-based modalities that have been co-opted and “rebranded” as CAM, such as exercise and nutrition—have no specific effects detectable above placebo effects, CAM advocates move the goalposts and claim that CAM works through the “power of placebo” and do their best to claim that “harnessing” that “power of placebo” is a justification to use their treatments. It turns out, however, that when placebo effects are examined rigorously there’s just not a lot of there there, so to speak. Results are underwhelming, and trying to “harness the power of placebo” without an intervention that actually impacts the pathophysiology of disease can even be dangerous. That’s not to say that learning to maximize placebo responses (whatever they are) while administering effective medical treatments isn’t important; rather, it’s to point out that, by themselves, placebo effects are not of much value.
Unfortunately, none of this has stopped what Steve Novella refers to as the “placebo narrative” from insinuating itself into lay discussions of medicine. That narrative proclaims in breathless terms (as Steve put it) the “surprising power of the placebo effect” without putting it into reasonable perspective or even really defining what is meant by “placebo effect.” First, as we have tried to explain time and time again here, there is no single “placebo effect.” There are placebo effects. Second, the only really correct reference to “the placebo response” or “placebo effect” is the outcome measured in the placebo arm of a clinical trial. The problem is that, all too often, discussions of placebo responses conflate the placebo effect measured in a clinical trial with all the other various placebo effects that add up to the response that is measured in that trial. Those effects include reporting biases, researcher biases, regression to the mean, conditioning, and many other components that contribute to what is measured in the outcome of a clinical trial. Another common misconception about placebo effects is that they are somehow “mind over matter,” that we can heal ourselves (or at least reduce our symptoms) through the power of will and mind. This is not true. Placebo effects are not the power of positive thinking.