Shaping placebo analgesic responses on the Internet: a randomized experimental trial

The field of Internet-based treatments is expanding. However, little is known about placebo effects in online therapeutic settings. The aim of this study was to test if placebo analgesia could be induced via online communication. Exploratory analyses tested if different communication styles (empathetic/neutral) would influence the placebo effect.

In this double-blind experiment, 30 healthy participants were randomized to either empathetic or neutral online communication. After completing the online modules, a face-to-face placebo analgesia experiment was performed. An independent experimenter (blinded as to communication type) performed the pain testing and treatment with a sham analgesic device (placebo).

Overall, there was a significant placebo effect, as participants rated the pain lower when the sham analgesic device was turned on, compared to off. An additional control experiment (n = 17) confirmed that pain testing with the sham analgesic device per se, without any prior communication, was not enough to induce placebo effects. Exploratory analyses indicated a significant difference in perception of the online communication between participants randomized to the empathetic and neutral groups because the empathetic group rated the interaction as more positive. Also, there was a significant difference in online compliance. Yet, exploratory analyses did not suggest any difference in placebo pain ratings between the empathetic and neutral communication groups.

The results in this study suggest that placebo effects can be created even when information about an analgesic treatment is delivered online. This is the first indication of a novel research line that investigates placebo effects in online treatment.