By Catherine A. Sanderson, Amherst College
One of the clearest illustrations of the link between cognition and pain is seen in the placebo effect, meaning a change that occurs when a person’s expectations or beliefs, rather than an actual drug or treatment, create an outcome. Placebo effects have been found to influence many different types of pain, including chest pain, arthritis, headaches, and postoperative pain.
In one simple demonstration, Europeans with frequent headaches were given pills labeled either Nurofen (a trusted brand name in Europe) or generic ibuprofen. Some of the people in each condition were given actual active ibuprofen and the other half were given placebo pills. Not surprisingly, those who received generic-label ibuprofen reported greater pain relief than those who took the placebo.
But here’s what was surprising: for the brand name label, people reported similar levels of pain relief regardless of whether they received actual ibuprofen under the brand label or a placebo with only the brand-name label. Furthermore, those people who took placebo pills with a brand name label reported greater headache relief than those who took the exact same placebo pills with a generic label. So, the label really does matter.
Price Matters, Too
And it’s not just brand names that create expectations; even believing a drug costs more, which we associate with higher quality, increases its effectiveness. Researchers in one study first gave all participants a light electric shock on their wrists.
Next, participants were told they would be receiving a newly-approved pain-killer to measure whether it would reduce their experience of pain. Half of the participants were told the pill cost $2.50 per dose; the others were told the drug had been marked down and only cost 10 cents.
The participants then took a pill, which in all cases contained no actual medicine. The researchers then again delivered an electric shock, and asked people whether they felt less pain. Sixty-one percent of those who took a placebo pill costing just 10 cents reported feeling less pain, compared to 85% of the people who took a placebo pill they believed cost $2.50.
The placebo effect is a clear demonstration that our thoughts about pain and pain relief matter. But how exactly does this work? One explanation is that when we expect a particular drug or procedure will help reduce our pain, we may change our behavior in ways that actually lead to beneficial effects.
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The Placebo Effect
One of the most vivid demonstrations of the power of our thoughts about pain was found by Bruce Moseley, an orthopedic surgeon at the Houston Veterans Affairs Medical Center. Men with osteoarthritis in their knees were randomly assigned to one of three groups:
Men in one group underwent standard arthroscopic knee surgery, which involves scraping of the knee joint. Men in a second group underwent surgery, but it only included a rinsing of the knee joint. Men in the third group underwent a surgery, but received no actual medical procedure; their knees were merely cut open with the scalpel to create a scar.
They were then assessed regularly over the next two years, asked to report on how much pain they were experiencing and whether they had increased function for engaging in daily life tasks, such as walking and climbing stairs. The findings were remarkable. There were no differences in amount of pain or daily life functioning between the men in the three groups at any point during the follow-ups. All three groups improved at the same rate.
Although the researchers couldn’t explain what led to the equivalent improvement, one possibility is that simply believing they had received surgery that would decrease pain and increase functioning changed their behavior. Another explanation is that belief in placebos may lead to physiological changes in the body. Simply believing that a drug will help reduce pain leads to the release of endorphins, which in turn reduces the experience of pain.
Placebos Change the Brain Response
Some recent research even demonstrates that placebos change how the brain responds to pain. In one study, researchers gave participants painful electric shocks to their wrists. Before they received the shocks, some people were given a cream that that they were told would reduce, but not eliminate, the pain.
Other people were given a cream that they told would have no impact on their experience of pain. In reality, the cream was the same in both conditions and had no pain-relieving properties. The researchers then measured the participants’ brain activity. As predicted, participants who believed they received a pain-reducing cream showed decreased brain activity in parts of the brain that respond to pain.
This is a collection of brain areas sometimes called the pain matrix that includes the thalamus, the somatosensory cortex, the anterior cingulate cortex, and the insula or insular cortex. So, one explanation for the placebo effect is that it works at least in part by changing how these and other areas of the brain respond to pain.
Common Questions about the Placebo Effect
The placebo effect occurs when individual expectations and beliefs create the result instead of actual medication or treatment. This can positively influence different types of pain, including postoperative pain, arthritis headache, and chest pain.
The placebo effect shows that thoughts can also affect the experience of pain. One explanation for this phenomenon is that belief in placebos alone leads to physiological changes in the body. Simply believing that a drug helps reduce pain leads to the release of endorphins, reducing the level of pain sensations.
Yes. A collection of the brain areas includes the anterior cingulate cortex, the somatosensory cortex, the thalamus, and the insula—also called the pain matrix. The placebo effect works in a way that it changes the brain’s response to pain by altering the response of these areas to pain.