The increased analgesic efficacy of cold therapy after an unsuccessful analgesic experience is associated with inferior parietal lobule activation

한글 요약

이전 치료에서 실패한 경험이 이후에 받는 비약물 치료의 효과에 어떤 영향을 주는지를 fMRI로 살핀 연구입니다. 위약 진통 크림을 바른 뒤 열 자극 강도를 조작해 한 집단에는 효과가 거의 없었다는 부정적 경험을, 다른 집단에는 효과가 컸다는 긍정적 경험을 심어 준 다음, 뒤이어 냉찜질 치료를 받을 때의 통증 평가와 뇌 반응을 비교했습니다. 부정적 경험을 한 집단은 냉찜질에서 통증과 불안을 더 낮게 보고했고, 통증 완화에 관여하는 것으로 알려진 오른쪽 하두정소엽의 활동이 유의하게 더 컸습니다. 처음 받은 진통 치료가 만족스럽지 못했던 경험이 보완적 치료에 대한 기대를 높여 진통 효과를 키울 수 있으며, 그 과정에 하두정소엽이 관여함을 시사하는 결과입니다.

Prior experiences of successful and failed treatments are known to influence the efficacy of a newly applied treatment. However, whether that carry-over effect applies to non-pharmacological treatments is unknown. This study investigated how a failed treatment history with placebo analgesic cream affected the therapeutic outcomes of cold-pack treatment. The neural correlates underlying those effects were also explored using functional magnetic resonance imaging. The effect of the placebo analgesic cream was induced using placebo conditioning with small (44.5 °C to 43.7 °C, negative experience) and large (44.5 °C to 40.0 °C, positive experience) thermal stimuli changes. After the placebo conditioning, brain responses and self-reported evaluations of the effect of subsequent treatment with a cold-pack were contrasted between the two groups. The negative experience group reported less pain and lower anxiety scores in the cold-pack condition than the positive experience group and exhibited significantly greater activation in the right inferior parietal lobule (IPL), which is known to be involved in pain relief. These findings suggest that an unsatisfying experience with an initial pain-relief treatment could increase the expectations for the complementary treatment outcome and improve the analgesic effect of the subsequent treatment. The IPL could be associated with this expectation-induced pain relief process.