A physician’s expectation as to whether or not a treatment will be successful may lead to a patient experiencing less pain and having a better outcome, according to researchers at Dartmouth.

In a single blind study, the researchers simulated a series of clinical interactions between 48 participants: 24 pairs of physician-patient teams who were tasked with evaluating the efficacy of 2 different treatments while undergoing thermal pain. The same amount of heat of 47°C/116.6°F was applied to each arm.

The study was comprised of 3 experiments using 2 creams intended to alleviate thermal pain by targeting skin pain receptors. The creams, "thermedol" and a control cream, were 2 different colors; however, both were the placebo: the petroleum-based jelly, Vaseline. After each topical cream was applied to a participant's arm, they received thermal heat and self-assessed the efficacy of the cream. The self-administered report allowed participants to indicate how much pain they experienced, their physiological response, and their facial expression behaviors.

With the “thermedol” treatment, patients reported less pain and indicated that they believed this treatment was more effective than the control cream. In addition, patients had a lower skin conductance response, demonstrating decreased psychophysiological arousal with this treatment.

The other 2 studies switched the order in which the 2 creams were administered. This ruled out that the relationship between physicians’ expectations about the efficacy of a treatment and patients’ experiences of pain were not due to habituation or extinction.

When the physicians believed that a treatment would work, patients appeared to experience less pain based on their subjective reports after treatment. The study found that social interactions between hypothetical health care providers and patients have the power to influence a patient’s perception on the efficacy of a treatment, regardless of whether or not it was a placebo.

  1. Chen P.H, Cheong J.H, Jolly E, et al. Socially transmitted placebo effects. Nature Human Behaviour, 2019 DOI: 10.1038/s41562-019-0749-5