Scientists have known since at least the 1930s that a doctor’s expectations and personal characteristics can significantly influence a patient’s symptom relief. Within research contexts, avoiding these placebo effects is one reason for double blind studies — to keep experimenters from accidentally biasing their results by telegraphing to test subjects what they expect the results of a study to be.
Students in the doctor group had previously been conditioned to believe that one of the creams was pain reliever. But in reality both of the two creams that they administered were an identical petroleum jelly-based placebo. And yet, when the doctor actors believed that the cream was a real medication — the researchers even gave the pseudo-medication a name, “thermedol” — the patient actors reported experiencing significantly lower amounts of pain.
As well-documented as the placebo effect is, to see it play out so cleanly surprised the study’s authors themselves. “We did several more studies to convince ourselves it wasn’t just a fluke,” says the study’s primary author, Luke Chang of Dartmouth University. “I’m impressed at how robust the effect seems to be.”
It seems that this damned placebo effect is getting in the way of developing and authorising new psychiatric drugs. It creates a ‘therapeutic bias'(!) and so the experimenters are experimenting with ways of controlling for it in trials, for example ‘SPCD, sequential parallel comparison design’. These are proving to be not (yet) up to the task, sufficient to be acceptable by bodies such as the RDA. The following is from The Placebo Effect Is Hobbling New Psychiatric Drugs
“The FDA’s rejection cast doubt upon the design, still in use in more than a dozen trials, as a weapon against the placebo effect.
That’s big news because the effect, also called the placebo response, has been growing stronger over the years in clinical studies that randomly assign patients to either an active drug or placebo. When the effect is high, it’s hard to know if a drug just isn’t good enough, if there are errors in the data, or if the participants taking the placebo—an inert pill meant to make them believe they’re getting the real thing—fared unusually well because of their expectations.
It’s a testament to the power of our minds to improve our health, at least temporarily. Many factors boost placebo response. “Most people, whether they know it or not, are biased to believe that they will receive the active drug even if they are told that they have a 50 percent chance of getting placebo, and this ‘therapeutic bias’ increases the placebo response,” says John Krystal, the chair of the psychiatric department at the Yale School of Medicine in New Haven, CT.”
There is some evidence – for example, in this study – that simply receiving the results of DNA tests can have a physical impact. Why? Well, once more the Placebo Effect is mentioned (as well as its dark twin, the Nocebo Effect, also covered on this website.
DNA tests are becoming quicker, cheaper and more reliable, so this is an issue we’ll hear more about.
Pain is something of a mystery. While we all experience it, and experience it in degrees, there’s no ‘gold standard’ for estimating the degree of pain. It seems to be a ‘subjective’ experience. In some of the research literature, such as this study, the placebo effect is given a credible place in the landscape of pain and pain management.
“Placebo effects that arise from patients’ positive expectancies and the underlying endogenous modulatory mechanisms may in part account for the variability in pain experience and severity, adherence to treatment, distinct coping strategies, and chronicity. Expectancy-induced analgesia and placebo effects in general have emerged as useful models to assess individual endogenous pain modulatory systems.”
Meantime, in the category of ‘Out There But Maybe Not As Out There As You Might Think’ virtual reality may have the capacity to harness the placebo effect in pain management.
“Recently, Cedars-Sinai also published research on the clinical utility of a virtual reality intervention in the Inpatient setting. The results of the study were overwhelmingly positive with most patients receiving pain and stress relief from the VR experience.”
We’ve posted elsewhere about the placebo’s dark twin, the nocebo, the phenomenon of the mind provoking negative and damaging effects through the same mechanism that accounts for the positive effects of a placebo.
This paper brings focus to ‘nocebo algesia and hyperalgesia (ie, the occurrence and worsening of nocebo-induced pain, respectively)’ and makes practical suggestions for reducing the incidence of this. As always, these relate to the patient-practitioner relationships and interactions, and strongly reinforce the ‘subjective’ and ‘negotiated’ nature of the experience of pain.
‘In general, the literature shows that uncaring interactions that convey a message of invalidation and lack of warmth may trigger nocebo effects. Avoiding negative communication and interactions with a patient may help to shape a safe and positive environment that not only promotes placebo effects but that also reduces nocebo effects.’
What you expect is often what you get, and the placebo effect is at work! We have noted elsewhere that one possible account for the engagement of the placebo effect is the wish to ‘please the physician’, to be a ‘good patient’. According to this Stanford study, this might come as only a few positive words. “… When a health care provider offers a few encouraging words about their patient’s recovery time from an allergic reaction, symptoms are significantly reduced.”
Similarly expectations about the benefit of exercise can be seen to actually impact on life expectancy outcomes. In this study “the team looked at death rates. They used statistical models to account for other factors linked to death, such as age, chronic illnesses, and body mass index (BMI). Even accounting for these risk factors, those who saw themselves as less physically active were 71% more likely to die in the 21 years following the original survey.”
An article in Big Think entitled People are knowingly taking placebos—and its working starts to untangle some of the theories about the functionality of ‘open label’ placebos – which describes the engagement of a placebo effect even when people know they’re taking a placebo.
“Even though they were told that what they were taking was placebo and contained nothing of therapeutic value, those patients who received the placebo reported a 30% reduction in usual pain and maximum pain and a 29% drop in their disability. Incredibly, the placebo worked better than the real pain medication. Participants who took the pain pills reported feeling 9% less usual pain, and 16% less maximum pain. Furthermore, patients taking the real medication reported no change in their level of disability.”
Pain is a subjective state – that’s why practitioners typically ask us to ‘scale’ our experience of it, from a ‘1’ (slight) to a ’10’ (unbearable). And while it’s easy to see why the experience of pain is useful in an evolutionary sense (‘keep your hand out of the fire!’) it’s difficult to account for what mechanism is responsible for this experience. Different analgesics may have different effects (and affects) for different people, and some don’t seem to contraindicate – it seems you can ingest an opioid at the same time as paracetemol.