Graeff Philipp, Itter Alina, Wach Katharina, Ruscheweyh Ruth
Graduate School of Systemic Neuroscience, Ludwig-Maximilians-University Munich, 82152 Planegg, Germany.
Research Training Group (RTG) 2175 Perception in Context and Its Neural Basis, Ludwig-Maximilians-University Munich, 82152 Planegg, Germany.
Brain Sci. 2021 Sep 9;11(9):1186. doi: 10.3390/brainsci11091186.
Conditioned pain modulation (CPM) describes the reduction in pain evoked by a test stimulus (TS) when presented together with a heterotopic painful conditioning stimulus (CS). CPM has been proposed to reflect inter-individual differences in endogenous pain modulation, which may predict susceptibility for acute and chronic pain. Here, we aimed to estimate the relative variance in CPM explained by inter-individual differences compared to age, sex, and CS physical and pain intensity. We constructed linear and mixed effect models on pooled data from 171 participants of several studies, of which 97 had repeated measures. Cross-sectional analyses showed no significant effect of age, sex or CS intensity. Repeated measures analyses revealed a significant effect of CS physical intensity ( = 0.002) but not CS pain intensity ( = 0.159). Variance decomposition showed that inter-individual differences accounted for 24% to 34% of the variance in CPM while age, sex, and CS intensity together explained <3% to 12%. In conclusion, the variance in CPM explained by inter-individual differences largely exceeds that of commonly considered factors such as age, sex and CS intensity. This may explain why predictive capability of these factors has had conflicting results and suggests that future models investigating them should account for inter-individual differences.
条件性疼痛调制（CPM）是指当测试刺激（TS）与异位疼痛条件刺激（CS）同时呈现时，由测试刺激诱发的疼痛减轻。有人提出CPM反映了内源性疼痛调制的个体差异，这可能预测急性和慢性疼痛的易感性。在这里，我们旨在估计与年龄、性别、CS物理强度和疼痛强度相比，个体差异所解释的CPM相对方差。我们对来自几项研究的171名参与者的汇总数据构建了线性和混合效应模型，其中97人有重复测量。横断面分析显示年龄、性别或CS强度无显著影响。重复测量分析显示CS物理强度有显著影响（ = 0.002），但CS疼痛强度无显著影响（ = 0.159）。方差分解表明，个体差异占CPM方差的24%至34%，而年龄、性别和CS强度共同解释的比例小于3%至12%。总之，个体差异所解释的CPM方差在很大程度上超过了年龄、性别和CS强度等通常考虑因素的方差。这可能解释了为什么这些因素的预测能力会产生相互矛盾的结果，并表明未来研究它们的模型应该考虑个体差异。
