中国科学院心理健康重点实验室知识库

Nondeceptive placebo has demonstrated its efficiency in clinical practice. Although the underlying mechanisms are still unclear, nondeceptive placebo effect and nondeceptive nocebo effect may be mediated by expectation. To examine the extent to which expectation influences these effects, the present study compared nondeceptive placebo and nocebo effects with different expectation levels. Seventy-two healthy female participants underwent a standard conditioning procedure to establish placebo and nocebo effects. Sequentially, participants were randomized to one of the four experimental groups-baseline (BL), no expectation intervention (NoEI), expectation increasing (EI), and expectation decreasing (ED) groups, to receive either no intervention or interventions through different verbal suggestions that modulated their expectation. Placebo and nocebo effects were established in all four groups after the conditioning phase. However, after disclosing the placebo and nocebo, the analgesic and the hyperalgesic effects only persisted in the EI group, when compared with the BL group. Our results provide evidence highlighting the critical role of increased expectation in nondeceptive placebo and nocebo effects. The finding suggests that open-label placebo or nocebo per se might be insufficient to induce strong analgesic or hyperalgesic response and sheds insights into administrating open-label placebo and avoiding open-label nocebo in clinical practice.

The work was supported by the National Natural Science Foundation of China (nos 31471082, 31671141, 31701000, and 31771240), Chongqing Research Program of Basic Research and Frontier Technology (no. cstc2015jcyjBX0050), the Scientific Foundation Project of Institute of Psychology, Chinese Academy of Sciences (nos Y6CX021008 and Y6CX281007), and Cognition and Human Behavior Key Laboratory of Hunan Province, Hunan Normal University (CBL201605). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.