Expectancy-induced placebo analgesia in children and the role of magical thinking.

UNLABELLED Expectations and beliefs shape the experience of pain. This is most evident in context-induced, placebo analgesia, which has recently been shown to interact with the trait of magical thinking (MT) in adults. In children, placebo analgesia and the possible roles that MT and gender might play as modulators of placebo analgesia have remained unexplored. Using a paradigm in which heat pain stimuli were applied to both forearms, we investigated whether MT and gender can influence the magnitude of placebo analgesia in children. Participants were 49 right-handed children (aged 6-9 years) who were randomly assigned-stratified for MT and gender-to either an analgesia-expectation or a control-expectation condition. For both conditions, the placebo was a blue-colored hand disinfectant that was applied to the children's forearms. Independent of MT, the placebo treatment significantly increased both heat pain threshold and tolerance. The threshold placebo effect was more pronounced for girls than boys. In addition, independent of the expectation treatment, low-MT boys showed a lower tolerance increase on the left compared to the right side. Finally, MT specifically modulated tolerance on the right forearm side: Low-MT boys showed an increase, whereas high-MT boys showed a decrease in heat pain tolerance. This study documented a substantial expectation-induced placebo analgesia response in children (girls > boys) and demonstrated MT and gender-dependent laterality effects in pain perception. The findings may help improve individualized pain management for children. PERSPECTIVE The study documents the first experimental evidence for a substantial expectancy-induced placebo analgesia response in healthy children aged 6 to 9 years (girls > boys). Moreover, the effect was substantially higher than the placebo response typically found in adults. The findings may help improve individualized pain management for children.