Background: Nonpharmacologic stress reduction interventions provide an opportunity to modify chronic pain trajectories; however, the biological mechanisms underlying these interventions are poorly understood.
Objectives: To examine clinical literature published in 2012-2018 with the goals of (1) identifying which biological mechanisms or biomarkers are currently being measured in nonpharmacologic stress reduction intervention studies for individuals with chronic pain and (2) evaluating the evidence to determine whether these stress reduction interventions lead to changes in (a) pain outcomes and/or (b) measured biomarkers.
Data sources: Scientific articles in the electronic databases PubMed/Medline, Cumulative Index of Nursing and Allied Health Literature, PsychINFO, and SCOPUS following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.
Study selection: Randomized controlled trials and quasi-experimental studies that recruited subjects with a chronic pain condition, examined a relationship between a nonpharmacologic stress reduction intervention and pain-related outcome(s), and included measurement of a biomarker.
Results: The 13 articles that met inclusion criteria spanned four nonpharmacologic stress reduction categories: mindfulness-based stress reduction, physical exercise, manual therapies, and biofeedback. Methods for studying biomarkers included measuring biological samples, neurological function, and autonomic control. Although all studies investigated both biological measures and pain outcomes, only three demonstrated an association between the biomarker(s) and pain-related outcomes.
Conclusions: The results of this review highlight the complex nature of stress-pain relationships and the lack of rigorous clinical research identifying specific stress-related biological factors that modulate pain outcomes. Stress reduction interventions remain a favorable method for symptom management in patients living with chronic pain, but consistency in study measures and design is needed for robust evaluation.
Keywords: biomarkers; chronic pain; nonpharmacologic intervention; psychological stress; stress reduction intervention.