The Placebo Effect – 10 Amazing Findings

March 12, 2019

The placebo effect usually triggers an eye-brow raise or two among even the most hard-nosed of skeptics. We may not be able to forecast the future or move physical objects with our minds, but the placebo effect is nearly as marvellous (Ben Goldacre once called it the “coolest, strangest thing in medicine”).

The term “placebo effect” is short-hand for how our mere beliefs about the effectiveness of an inert treatment or intervention can lead to demonstrable health benefits and cognitive changes – an apparently incontrovertible demonstration of the near-magical power of mind over matter.

It’s not literally magic, of course. Our beliefs are the subjective echo of physical processes in the brain – and it’s this constellation of neurochemical and electrical events , and their downstream effects, that underlies the placebo phenomenon (in some cases the placebo effect can also be interpreted as a form of conditioned response, in which a learned physiological reaction occurs in the absence of the original trigger).

There is another angle to this topic. To research psychologists, the placebo effect isn’t always a phenomenon of wonder, but a methodological nuisance. Researchers must go to extreme lengths to rule out the influence of participant expectations, so as to establish which observed effects are truly attributable to an intervention.

Here, in a celebration of the mysterious and maddening placebo effect, and to help inspire future research into this most fascinating aspect of human (and animal) psychology, we digest 10 amazing placebo-related findings:

The Placebo Effect Works Even When You Know It’s A Placebo

For the placebo effect to occur, it’s usually considered that deception is required – tricking the patient into thinking that an inert treatment is actually a powerful drug or similar. It’s this need for trickery that has long meant the deliberate inducement of placebo effects in mainstream medicine is seen as unethical. Nearly ten years ago, however, researchers showed that people with irritable bowel syndrome showed greater improvement after being given a so-called “open placebo” that they were told was completely inert, as compared to receiving no treatment.

Presumably some residual belief and expectation of an effect survives being told that the treatment is physically impotent (or there is a condition response to the placebo that does not require positive beliefs). More recent research has since shown benefits of open placebos for many other conditions including back pain and hay fever.

Open placebos “bypass at least some of the conventional ethical barriers” to the clinical use of placebos, according to some experts. Others however have highlighted the lack of  suitably robust research in this area, and it’s worth noting there have been some null findings – for instance, open placebos failed to speed up wound healing.

Branding, Colours and Medical Paraphernalia Can All Boost The Placebo Effect

Putting aside open placebos, there’s evidence that different forms of deceptive placebo vary in their effectiveness. The more powerful we imagine their effect will be, the larger the benefit. This means that four placebo pills have a larger effect than two; and placebo injections (filled with nothing other than saline solution) are more powerful than pills (in fact, in the context of osteoarthritis, a placebo injection was found to be more effective than a real drug).

Also – depending on the condition being treated – pills of certain colours and descriptions are more effective than others, such as blue placebo pills making better sedatives than pink ones, and branded placebo pills being more effective than those without any labelling. The influence of the credibility of a given placebo on its subsequent effectiveness may help explain one of the most astonishing demonstrations of the placebo effect that I’ve come across. It involved “placebo brain surgery” – and what could elicit a greater hope for a treatment effect than the elaborate paraphernalia and protocols involved in experts operating on your brain?

Specifically, the research showed that patients with Parkinson’s Disease who undertook a form of placebo brain surgery (supposedly, but not really, involving the injection of stem cells) showed greater symptom improvements than those patients who received the stem cell treatment, but didn’t think they had. “The placebo effect was very strong in this study,” the researchers said, “demonstrating the value of placebo-controlled surgical trials.”

Some People Are More Prone To The Placebo Effect Than Others

Certain personality traits are associated with it being more likely that a person will experience the placebo effect. This is logical since the placebo effect depends on our beliefs and expectations, which some of us may subscribe to more readily and enthusiastically than others.

Among the results in this area, optimists are more responsive to analgesic placebos, as are people who score higher for emotional resilience and friendliness (this last finding may relate to the social dynamic involved in the elicitation of the placebo effect by physicians). Curiously, the traits related to placebo response vary according to the condition being treated – in the context of stress, for instance, one study found it was the more pessimistic and less empathic participants who showed a greater placebo response.

Whereas personality traits appear to play an important role in the placebo effect, the evidence to date suggests that age and gender are largely irrelevant.

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