title: Cognitive manipulation targeted at decreasing the conditioning pain perception reduces the efficacy of conditioned pain modulation.
abstract: Although painfulness of the conditioning stimulus (CS) is required for the activation of conditioned pain modulation (CPM), it is still unclear whether CPM expression depends on the objective physical intensity of the CS or the subjective perception of its pain. Accordingly, we cognitively manipulated the perceived CS pain, rendering the physical aspects of the CPM paradigm untouched. Baseline CPM was measured among 48 young healthy male subjects using the parallel paradigm with contact heat as test pain and hand immersion in hot water as CS. Subjects were then randomized into 4 groups, all of which were cognitively manipulated as to the CS-induced pain: group 1, placebo (CS less painful); group 2, nocebo (CS more painful); and groups 3 and 4, the informed control groups for groups 1 and 2, respectively. CPM was reassessed after the manipulation. Comparing the groups by MANCOVA (multivariate analysis of covariance) revealed that placebo exerted decreased CS pain and consequent attenuation of CPM magnitudes, while nocebo elicited increased CS pain, but without CPM elevation (P<.0001). Within the placebo group, the reduction in CS pain was associated with diminished CPM responses (r=0.767; P=.001); however, no such relationship characterized the nocebo group. Pain inhibition under CPM seems to depend on the perceived level of the CS pain rather than solely its physical intensity. Cognitively decreasing the perceived CS pain attenuates CPM magnitude, although a ceiling effect may limit CPM enhancement after cognitively increased CS pain. These findings emphasize the relevance of cognitive mechanisms in determining endogenous analgesia processes in humans.
authors: Department of Neurology, Rambam Health Care Campus, Haifa 31096, Israel Laboratory of Clinical Neurophysiology, Faculty of Medicine, Technion, Israel Institute of Technology, Haifa 31096, Israel Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa 31905, Israel.
authors: Rony-Reuven
authors: RR
authors: Nir
authors: David
authors: D
authors: Yarnitsky
authors: Liat
authors: L
authors: Honigman
authors: Michal
authors: M
authors: Granot
mesh_terms: D000328:Adult; D000698:Analgesia / Q000523:psychology*; D003071:Cognition / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement / Q000523:psychology; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology