To study whether an experimental drug is effective, it is compared to one that looks, smells, and tastes the same yet lacks any active ingredients: a placebo. By keeping patients unaware of which pill they are taking in studies, researchers can learn if the differences in outcomes are due to the medication itself or simply the power of suggestion.
Okay, you know that much—but here are ten things that will surprise you about placebo pills and the placebo effect.
- What’s in a name? The term placebo is derived from the Latin verb placere, meaning “to please.”
- What’s in a placebo pill? Only 8% of trials share what the contents of their placebo pill is. In fact, the FDA does not have rules about what is in or not in a placebo pill. Could it be that placebo pill contents (sugars, starch, saline, etc) have some benefits? We don’t know.
- What accounts for the placebo response? It is generally accepted that the placebo response (people who get “better” while taking placebo) reflects a mind/body interaction that is evoked by psychological factors: expectations, beliefs, and wishful thinking. More on this later.
- Placebo response is rising. Interestingly, the placebo response has continued to rise over time. For example, in folks with depression, before 2001 29% of those taking placebo reported improvement compared to 36% after 2001. No idea why this is happening.
- IBS and placebo. In recent trials on treatments for irritable bowel syndrome (IBS), the placebo response rate was as high as 59%! So almost 60% of IBS patients improved while taking a pill with inactive ingredients. Study authors believe these high placebo response rates in patients with IBS, a condition that has no easy cure, may represent the power of their desire for the treatment to be effective.
- Depression and placebo pills. This has plagued many antidepressant medication trials: the placebo response is so high that in comparison the antidepressant medication looks ineffective. Some argue that one reason for the “success” rates of antidepressants is the rising placebo response. Less than 50% of trials demonstrate superiority for antidepressants over placebo.
- Placebo effect and the brain. Brain MRI studies on folks with depression taking a placebo pill for treatment have found that placebo pills evoke changes comparable to those of an SSRI (selective serotonergic reuptake inhibitor)—they improve mood and reduce depression.
- Why are some people more susceptible to placebo effects? Functional MRI and PET scans are been used to reveal how the brain is activated during placebo response, but also to predict who may respond to placebo. Recent evidence has found that placebo response may be predetermined by brain biology. In other words, brain imaging identified ahead of time those who were going to respond to placebo, by their “right mid frontal gyrus extent of functional connectivity.” Cool, right?
- What is healing? Some researchers wonder if the therapeutic intervention that comes along with placebo in a research study (a visit to your doctor, communication with a healthcare practitioner, lab work, etc) contributes to improvement, rather than the pill itself.
- Communication and wellbeing. In clinical trials there are many scheduled visits, examinations and consultations. Can the improvement seen in those taking an inactive pill be partially explained by that communication, and by activation of the patient’s self-healing power? Is the placebo effect really just the patient’s self-healing power resulting from trust and belief in the treatment process?