Investigating associations between allostatic load phenotypes and clinical impairment in youth with chronic pain.

Allostatic load (AL), defined as nervous system wear and tear in response to repeated or prolonged stress, has been hypothesized to underlie risk for the onset and/or maintenance of chronic pain. However, minimal research has directly examined the measurement and interpretation of AL in relation to chronic pain in clinical populations. Recent work in a community sample of adults suggests relations between chronic pain and "allostatic load phenotypes" (e.g. parasympathetic dysregulation and metabolic dysregulation), where the metabolic dysregulation phenotype showed to predict greater pain interference and a higher number of pain sites compared to low allostatic load phenotype. Given the dearth of understanding on how AL manifests in youth with chronic pain, the current study aimed to investigate AL phenotypes in youth with chronic pain and their associations with clinical outcomes. Allostatic load measures, including salivary cortisol, dehydroepiandrosterone (DHEA), and C-reactive protein, as well as waist-hip ratio, body-mass index, and blood pressure, were collected during previously scheduled new patient evaluations at a tertiary pain clinic. Results indicate biomarkers related to cardiovascular and cortisol phenotypes show good fit with the data. Further, youth with high cardiovascular risk and low cortisol risk evidenced greater pain catastrophizing, and those with high Cortisol risk evidenced greater exposure to childhood adversity. Future research should continue to examine the manifestation of these phenotypes in larger and broader chronic pain populations in youth and capture how these phenotypes may respond to intervention.