ORIGINAL RESEARCH article
Front. Pain Res.
Sec. Pain Research Methods
Volume 6 - 2025 | doi: 10.3389/fpain.2025.1621810
Is there a difference between heat-capsaicin induced low back pain and placebo for neural oscillations and inflammatory blood markers? An experimental randomized crossover study
Provisionally accepted
- 1Memorial University of Newfoundland, St. John's, Canada
- 2Central Queensland University, Brisbane City, Australia
- 3Canadian Memorial Chiropractic College, Toronto, Canada
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Purpose: Low back pain is difficult to study due to heterogeneity. Inducing back pain experimentally, with an established model such as heat-capsaicin, would beneficially control for some variability. How heat-capsaicin affects neurophysiological factors relevant to back pain is currently unknown, therefore, this study used a randomized crossover design with the aim to explore the differences between heat-capsaicin and placebo on brain activity and blood markers.Methods: 18 healthy participants completed two sessions: heat-capsaicin (45°C heat + capsaicin) and placebo (reduced heat + placebo). Pre-and post-induction/placebo electroencephalogram and blood draws were taken, and perceived pain was rated with a 100m visual analog scale. Band power was calculated for theta (4-8Hz), alpha (8-13Hz), beta (13-30Hz), gamma1 (30-58Hz), and gamma2 (62-100Hz) for six brain regions. An immune assay was run on plasma in duplicate for cytokines IL-1β, IL-6, IL-10, and TNFα.A repeated measures ANCOVA was run for all variables comparing between conditions (heat-capsaicin, placebo) with baseline measures as covariates. A Pearson's correlation was used to determine the relationship between perceived pain.The heat-capsaicin model induced transient mild to moderate pain which was significantly higher than placebo (24.50 vs 0.39; p<0.001). Brain wave and blood biomarkers were not significantly different between heat-capsaicin and placebo (p≥0.05) or correlated to perceived pain ratings (p≥0.15).Levels of perceived pain did not relate to neurophysiological changes that may occur immediately after heat-capsaicin exposure. Although changes have been found with other pain models and clinical pain, a statistically significant systematic response was not measurable using blood cytokine markers immediately after pain induction and may take longer to develop.
Keywords: experimental low back pain, heat-capsaicin, Electroencephaloagraphy (EEG), Cytokines, placebo, Brainwaves, EEG band power
Received: 01 May 2025; Accepted: 25 Aug 2025.
Copyright: © 2025 Frey, Summers, Power, C. K. Duarte and De Carvalho. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Diana E De Carvalho, Memorial University of Newfoundland, St. John's, Canada
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