A study presents physiological evidence that treatments honestly presented as placebos can still provide benefits.

A man consults with a nurse to sign forms for a clinical trial to accompany the article, "A placebo may have value even if a person knows what it is."Share on Pinterest
A new study suggests that placebos may have beneficial effects even if a person knows that they are receiving a placebo.

When a person receives treatment, it is natural for them to expect, or at least hope, that it will provide some benefit. Sometimes this expectation alone can produce a positive effect, as often occurs in studies where participants unknowingly receive a placebo instead of actual medication.

Now, a new study finds that even when researchers tell people that what they will receive contains no active ingredients, a placebo can produce a positive neurobiological effect.

The study, from researchers at Michigan State University, University of Michigan, and Dartmouth College, is published in Nature Communications.

In clinical trials, researchers do not typically inform control-group participants they have been given placebos that contain no active ingredients.

Such “deceptive” placebos sometimes appear to produce benefits, which suggests they may have value on their own as a safe, inexpensive means of helping patients.

However, the study notes that “an important ethical issue prevents their widespread use: the ubiquitous belief that for placebos to be effective, a person needs to be deceived into believing they are taking an active treatment.”

The study investigates the potential of “nondeceptive” placebos. With these substances, researchers inform individuals about how placebos are used, and that they will receive a placebo that may provide beneficial effects.

“Placebos are all about ‘mind over matter.’ Nondeceptive 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.”

– study co-author Jason Moser, Michigan State University, East Lansing, Michigan

The study notes that earlier research involved individuals self-reporting beneficial effects from nondeceptive placebos. These were for conditions that included irritable bowel syndrome, experimental pain, chronic back pain, a lack of psychological well-being, emotional distress, and poor sleep quality.

However, researchers consider such self-reports to be less empirically reliable and convincing than physiological measurement of effects.

There have been a few studies that investigate possible physiological changes produced by nondeceptive placebos.

The authors of the current study suggest previous researchers may have been looking in the wrong place, seeking improvements in areas that may be less responsive to the placebo effect, such as wound-healing recovery rates and physical skin reactions.

By contrast, the new study looks at the brain’s emotional stress levels as a more plausible target for a placebo effect.

The authors conducted two experiments where participants viewed 40 emotionally charged images. Thirty of these images were negative, while ten were neutral.

In both investigations, participants in the main cohort read materials explaining the placebo effect.

The experimenters then instructed the participants to inhale a saline-solution nasal spray and informed them this was a placebo. They also told them this substance could reduce the emotional impact of the images they were about to view.

By contrast, the control group participants did not learn about the placebo effect. Although they inhaled the same spray, they were told it was meant to enhance the accuracy of sensor readings to be taken as they viewed the images.

In the first experiment, individuals self-reported the nondeceptive placebo effect on their response to the images. As the researchers expected, these participants reported a reduction in the stressful impact of the pictures.

The second experiment used EEG readings to assess changes in stress-related neural activity as participants viewed the images.

The authors saw a gradual reduction of activity during the time window in which the brain was developing an emotional response to an image.

This suggests the nondeceptive placebo was physiologically calming the participants.

Co-author Ethan Kross of the University of Michigan in Ann Arbor, Michigan, says, “These findings provide initial support that nondeceptive placebos are not merely a product of response bias — telling the experimenter what they want to hear — but represent genuine psychobiological effects.”

The study’s lead author Darwin Guevarra, postdoctoral fellow at the University of Michigan, sums up the study’s takeaway:

“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? These results raise that possibility.”

The researchers now want to explore the use of nondeceptive placebos for reducing COVID-19-related stress using real-life trials.