New research published in Nature Communications has found that placebos reduce brain markers of emotional distress even when people are aware they’re taking an inactive substance.
The placebo effect typically occurs when a person unknowingly receives a fake treatment. But a growing body of research indicates that the placebo effect can occur even when people are aware that they are taking an inactive pill.
The new study provides some of the first evidence that these non-deceptive placebos impact neural responses that are relevant to emotional processing, raising hopes they could be used in the treatment of certain mental disorders.
“Placebos are primarily used as comparison groups for other treatments, but I saw the translational potential of using them as interventions in themselves to help promote psychological and physical health. Then I recognized some of the barriers that prevented that from happening, so I wanted to see if we can address these issues,” explained lead researcher Darwin A. Guevarra (@GuevarraDarwin), a postdoctoral fellow at Michigan State University.
In two experiments with 280 participants in total, the researchers showed two separate groups of people a series of emotional images. Prior to this task, the participants were randomly assigned to a control or non-deceptive placebo group.
The non-deceptive placebo group members read about placebo effects and were asked to inhale a saline solution nasal spray. They were told that the nasal spray was a placebo that contained no active ingredients but would help reduce their negative feelings if they believed it would. The control group members also inhaled the same saline solution spray, but were told that the spray improved the clarity of the physiological readings the researchers were recording.
In the first experiment, participants in the non-deceptive placebo group self- reported less distress after viewing emotionally negative image compared to participants in the control group. In the second experiment, the researchers used electroencephalography to find that non-deceptive placebos reduced electrical brain activity reflecting how much distress someone feels.
In particular, the researchers found the non-deceptive placebos “decreased an objective neural marker of emotional distress during the appraisal stages of emotional processing.”
The findings indicate that “placebos can still work even if you know you’re taking a placebo,” Guevarra told PsyPost. “But like their deceptive counterpart, they will not work on everything. Emotional distress seems to be a good context that is very responsive to non-deceptive placebos.”
“These findings provide initial support that non-deceptive placebos are not merely a product of response bias – telling the experimenter what they want to hear — but represent genuine psychobiological effects,” added Ethan Kross, a co-author of the study.
The results are in line with some previous research, which has found preliminary evidence that non-deceptive placebos are associated with reductions in test anxiety and might help reduce the amount of opioid medication a person asks for.
The latter finding is “a tremendously consequential behavioral effect,” Guevarra explained. “We need to do large scale studies on how effective these interventions are for pain and emotional distress. It can help bring us closer to one day using it as an intervention.”
But scientists still have much to learn about non-deceptive placebos and their effects.
“How do dynamics between the person receiving the placebo and the person giving it influence the effect? What happens if you change the placebo object? We used a nasal spray. But what if it was a pill? Or what if it was something you don’t consume at all? How important is the ritual of consumption? How does this work outside of the lab? How effective is it in other distressing situations? These are just a few questions,” Guevarra said.
The study, “Placebos without deception reduce self-report and neural measures of emotional distress“, was authored by Darwin A. Guevarra, Jason S. Moser, Tor D. Wager, and Ethan Kross.
