Open-label placebo effects on psychological and physical well-being: A conceptual replication study

Background: Contrary to traditional placebos, open-label placebos (OLP) abstain from deception, i.e., participants are openly informed to receive an inert substance. Studies in clinical and healthy samples evidence the efficacy of OLPs. This study aims to conceptually replicate and expand findings of a recent OLP study in healthy participants while implementing a within-subject design and daily instead of retrospective assessments. Additionally, the effect of a brand name on the medicine container is tested and possible predictors of the OLP effects are explored. Method: Healthy participants (N = 75) received OLP and no placebo for 5 days each (randomized sequence) and answered daily questionnaires on sleep quality, bodily symptoms, mental well-being, and psychological distress. The medicine container of half the participants had a brand name, the remaining did not. Different personality traits and situational factors were assessed. Results: Mental and physical well-being did not differ between OLP and control phase, i.e., overall, no OLP effect emerged. Contrast analysis indicated that an OLP effect emerged for sleep quality and psychological distress when no brand name was present. Further, an OLP effect emerged in persons with higher expectations for bodily symptoms (r = .23, p = .046) and psychological distress (r = .24, p = .037). Conclusions: Methodological differences to the original study are discussed as an explanation for the failure to induce overall OLP effects. Future studies should continue to replicate previous findings and determine the exact conditions of successful implementation of OLP effects in healthy as well as clinical samples. peerReviewed publishedVersion

背景：与传统安慰剂不同，开放标签安慰剂（open-label placebos, OLP）无需实施欺骗性操作，即公开告知参与者将接受惰性物质。针对临床及健康人群样本的多项研究已证实OLP的有效性。本研究旨在对近期一项针对健康人群的OLP研究结果进行概念性重复与拓展，同时采用被试内设计（within-subject design），并使用每日评估替代回顾性评估（retrospective assessments）。此外，本研究还检验了药品容器的品牌名称对效应的影响，并探索了OLP效应的潜在预测因素。方法：75名健康被试分别接受OLP干预与无安慰剂对照，每种干预持续5天，干预顺序为随机化安排。被试每日填写问卷，评估睡眠质量、躯体症状、心理幸福感与心理痛苦。半数被试使用带有品牌名称的药品容器，剩余被试使用无品牌名称的容器。同时评估了多项人格特质与情境因素。结果：整体而言，OLP干预与对照阶段的心理及躯体幸福感无显著差异，未观测到总体OLP效应。对比分析显示，当未使用品牌名称容器时，OLP对睡眠质量与心理痛苦产生了显著效应。进一步分析发现，在对躯体症状（r = 0.23, p = 0.046）与心理痛苦（r = 0.24, p = 0.037）有更高预期的人群中，OLP效应显著存在。结论：本研究与初始研究在方法学上的差异，可作为未观测到总体OLP效应的解释。未来研究应继续重复既往研究结果，并明确在健康人群及临床样本中成功实现OLP效应的具体条件。本研究为同行评审已发表版本。