A recent study has demonstrated that in certain circumstances, participants of an experimental study’s control group – aware of being treated with a placebo to ease pain – might still experience symptoms of relief.

The Truth Behind The Placebo Effect

It’s quite common – you’re not hungry, and then suddenly someone mentions food and you start salivating. Or you have a headache, and the moment you swallow an aspirin you feel the pain fading away, even though it hasn’t even been processed by your system. These are examples of the ‘placebo effect’, demonstrating the amazing and rather confounding abilities of the human mind.

CU-Boulder graduate student Scott Schafer, who works in Associate Professor Tor Wager’s Cognitive and Affective Neuroscience Lab in the Department of Psychology and Neuroscience, has provided interesting findings with regards to when the placebo effect works, and when it doesn’t. He observed that in certain cases, patients did experience relief from pain despite knowing that they were receiving ‘non-medical’ intervention.

Here’s the catch: the research participants need ample time – four sessions in the case of this study – to be conditioned so as to make the placebo work. Even if it is revealed later that the experimental intervention they are receiving has no medical basis, the participants will continue to experience relief. However, if the truth is revealed after only one session, the placebo effect will not kick in.

While performing the study, Schafer explained that his general interests were based on understanding of how humans predict their environment. Exploring how placebos occur – the when and why – was what really interested him.

Schafer, Wager, and co-author Luana Colloca, of the University of Maryland Baltimore, published their research entitled ‘Conditioned Placebo Analgesia Persists When Subjects Know They Are Receiving a Placebo’ in The Journal of Pain.

Refining and Confirming The Idea

For the study, Schafer and Colloca applied a heating element made out of ceramic on the forearms of the research subjects. Just enough heat was administered to induce strong sensations of pain and avoid burning the skin. An initial screening dismissed certain participants who had an unusually higher tolerance for pain.

After reaching temperatures of up to 117.5 degrees Fahrenheit, Schafer applied what the subjects were told was an analgesic to relieve the pain in the affected area of the forearm. The subjects thought that it would reduce the temperature and provide relief. The so-called analgesic was in fact Vaseline with blue food coloring presented in a pharmaceutical container.

To further substantiate the experiment, the participants were asked to read drug forms and inform the researchers whether they had any medical problems or had been taking other medications before enrolling in the study.

“They believed the treatment was effective in relieving pain”, stated Schafer, an obvious consequence of the placebo effect. He added that when the subjects were tested with and without treatment on medium intensity, they reported experiencing lesser pain with the placebo.

Key Findings In Terms Of Brain Functioning

Schafer claims that the findings could open new avenues for treating drug addiction and managing pain in children and adults who are prescribed strong, addictive pain killers post-op.“If a child has experience with a drug working, you could wean them off the drug, or switch that drug a placebo, and have them continue taking it”, Schafer explained.

Schafer further commented that these results highlight how the brain plays a vital role in making some people believe in placebo. He said that previous studies showed how placebos induced the release of pain-relieving chemicals in the brain. What was not clear was whether this expectation-independent placebo effect used similar or different mechanisms.

Conclusion

On the whole, the findings advocate that positive reinforcement can create a placebo effect and provide pain relief independent of reported expectations. Wager, the senior author, remarked that the research on placebos was still in preliminary stages. However, this study suggests that for a placebo effect to work, participants must believe in the influence of the treatment, and possess experiences consistent to those beliefs. The prior help the brain respond to the placebo as if it were a real intervention, and once the brain is conditioned into believing, the placebo can still have a positive effect even if you don’t believe it any longer.