Pain, Mindfulness and Placebo: a systematic review

Abstract

Pain is a complex phenomenon that is influence by psychosocial variables. Placebo can be included in the later factors that affect pain. The effectiveness of mindfulness-based interventions (MBI) in pain have been demonstrated by experimental studies and systematic reviews but the mechanisms of actions are just starting to be established. It remains to be evaluated in a systematic manner if the expectations of individuals experiencing pain are evaluated during MBI and if placebo effects can be manipulated in experimental settings. To evaluate the literature analyzing placebo effects in MBI for pain, we performed a systematic review based on a search conducted at the databases Pubmed, Web of Science and SCOPUS, between August and November of 2022. According to a defined mesh of search ("placebo" AND "pain" AND "mindfulness"), and inclusion/exclusion criterion a total of 17 studies were analyzed. From 22 papers initially included, 5 studies were excluded because they did not consider expectations or placebo effects in the studies, which already indicated that these variables are frequently discussed but not properly considered in the experimental design. From the 17 studies considered, 6 only analyzed the placebo effects of the pharmacological intervention used in the study and not of the MBI per se. The results of the few studies that were devoted to placebo effects of the MBI indicate that placebo and expectations play a role in the MBI effects in pain. The results indicate that MBI have a much larger effect on pain that placebo, suggesting that MBI may act by a placebo effect but there are other factors involved. Additional research in this fascinating and challenging field is necessary to fully understand the connection of MBI and placebo/expectations and their effects in pain relief.