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Placebos work even when people know what they are taking

The placebo effect may be more powerful than previously realized, according to a new study from Michigan State University. The researchers have demonstrated that treatments containing no active ingredients can reduce brain markers of emotional distress, even when people know they have been given a placebo.

The results of the study suggest that “non-deceptive placebos” can change how the brain reacts to emotional information.

“Recently, researchers have begun to examine whether the beneficial effects of placebos can be harnessed without deception by communicating to participants what placebos are, explaining the science behind how they work, and highlighting how placebos can still provide beneficial effects even if people know they are taking them,” wrote the study authors. 

“This verbal suggestion approach leverages one of the primary psychological mechanisms through which placebos operate: a person’s expectation that their condition will improve after receiving a treatment.”

Study lead author Darwin Guevarra is a postdoctoral fellow at MSU. 

“Just think: What if someone took a side-effect free sugar pill twice a day after going through a short convincing video on the power of placebos and experienced reduced stress as a result?” said Guevarra. “These results raise that possibility.”

The study was designed to investigate how effective a non-deceptive placebo may be for reducing emotional brain activity.

“Placebos are all about ‘mind over matter,” said study co-author Professor Jason Moser. “Non-deceptive placebos were born so that you could possibly use them in routine practice. So rather than prescribing a host of medications to help a patient, you could give them a placebo, tell them it can help them and chances are – if they believe it can, then it will.”

For the study, the researchers showed two separate groups of participants a series of emotional images. The non-deceptive placebo group members read about placebo effects and were asked to inhale a saline solution nasal spray. The individuals were told that the treatment was a placebo which contained no active ingredients but would help reduce their negative feelings if they believed it would. 

For comparison, members of the control group used the same saline solution, but were told that the spray improved the clarity of the physiological readings that were being recorded throughout the experiment.

The researchers found that the non-deceptive placebos substantially lowered levels emotional distress among the participants. In addition, non-deceptive placebos reduced electrical brain activity that represents how much distress someone feels in response to emotional events, and the reduction occurred within just a couple of seconds.

Study co-author Professor Ethan Kross said the findings provide initial support that non-deceptive placebos are not merely a product of response bias – telling the patient what they want to hear – but instead represent genuine psychobiological effects.

The research is published in the journal Nature Communications.

By Chrissy Sexton, Staff Writer


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