This question was originally posted on Quora.com and was answered by Huyen Nguyen, Professional Dabbler A fascinating study in 2015 made a remarkable finding: the placebo effect has become much stronger, but only in the U.S. studies! Researchers at McGill University (Canada) examined the impact of the placebo effect in 84 trials of pain treatments in the two decades between 1990-2013. Over that period, the pain inhibition experienced by patients in the placebo group increased steadily, reaching an average 30% decrease in pain levels by 2013. Similar increases in placebo response have previously been observed in studies of clinical trials of antidepressants and antipsychotic drugs. Based on patients’ ratings of their pain, the effect of trialled drugs in relieving symptoms remained the same over the 23-year period — but placebo responses rose. In 1996, patients in clinical trials reported that drugs relieved their pain by 27% more than did a placebo. But by 2013, that gap had decreased to a mere 9%. The phenomenon is driven by 35 US trials; and it doesn’t appear in trials in Europe, Asia and elsewhere. No one really knows why. But let’s go back a little to discuss what the placebo effect actually is because that’s very interesting in itself. Placebos are real and can produce measurable physiological changes such as faster heart rate or higher blood pressure. Illnesses that rely on the self-reporting of symptoms for measurement are most strongly influenced by placebos, such as depression, anxiety, irritable bowel syndrome and chronic pain. The placebo effect is a way for your brain to tell the body what it needs to feel better. The strength of the placebo effect can depend on the “dramatic” factor: an injection causes a stronger placebo effect than a pill, larger and more expensive pills are more ‘effective’ than cheaper ones. Even the color of pills can have an impact: hot colors induce a stimulant effect while cool colors a tranquilizing one. The weirdest thing is that even fake surgeries — where doctors make some incisions but don’t actually do anything — are an even stronger placebo than pills! A 2014 review of surgery placebos found that the fake surgery led to improvements 75% of the time. In the case of surgeries to relieve pain, one meta-review found essentially no difference in outcomes between the real surgeries and the fake ones! Nocebo (from the Latin “I shall harm”) is the flip side of placebo (Latin for “I shall please”). If a treatment is expected to be harmful, people are more likely to experience negative effects. If you tell a person that nausea is a common side effect of a pill, the person is more likely to report nausea even if they are actually taking a sugar pill! Placebos often work because people don't know they are getting one. More strangely, even when they DO know, it still works! A 2014 study gave a group of participants a placebo labeled "placebo," and discovered that the placebo was 50% as effective as the real drug to reduce migraine pain. This result is so bizarre that I’d love to see it replicated by others. The researchers behind the study speculated that even the simple act of taking a pill was having a positive impact. The placebo effect is a surrogate marker for everything that surrounds a pill: rituals, symbols and doctor care. People associate the ritual of taking medicine with a positive healing effect and trick themselves into feeling better. Going back to the 2015 study, one possible explanation is that the prevalence of direct-to-consumer drug advertising in America which is not allowed or common in other countries increases patients’ expectations of a medication’s efficacy. Another hypothesis is that clinical trials in the U.S. tend to be larger, longer and more elaborate, thus subconsciously raising the expectations of the participants. Before some people judge the Americans for being so gullible, another study also found that people who “scored high on resiliency, altruism, and straightforwardness, and low on measures of “angry hostility”” were more likely to experience a placebo effect. I’d be quite interested in whether the mental state of a person affects the placebo response. Wouldn’t it be quite plausible that a person living a more isolated life or having had less interaction with doctors might enjoy more benefits from being cared for and experience a stronger placebo effect? An implication is that a stronger placebo effect makes it harder to prove that a new medication is effective. Medications in both psychological and medical treatments are reported to have decreasing relative impact to placebos. In 2002, Merck was on the verge of releasing a new antidepressant MK-869 which had performed better than several other antidepressants on the market in early trials. Yet, MK-869 failed to beat a placebo treatment. In the last decade, more than 90% of new painkillers developed the U.S. suffered the same fate as MK-869. But don’t feel too depressed about this, this paper concludes: “antidepressant‐placebo differences are about the same for all of the sixteen antidepressants approved by the FDA in the past thirty years.” It looks like this gap varies from condition to condition and depends on culture as well. But before you get too excited about ‘mind over body’, the placebo effect isn’t magic. It doesn’t cure you. The fact that you feel better doesn’t mean that you are actually better. There is still an underlying physical condition that needs to be cured. And it’s not without controversy Does thinking make it so? CAM placebo fantasy versus scientific reality. But it is an intriguing phenomenon that can be exploited to augment existing medications. Source
