Background and aims
Stress and pain interact, and both are closely tied to fear learning: cortisol facilitates fear learning, while aberrant fear learning is hypothesized to be a contributing factor to the development and maintenance of chronic pain. Stress responses during fear learning have, however, not been investigated before, especially not in youth with chronic pain. We therefore aimed to assess stress responses over the course of a fear conditioning paradigm in youth with chronic pain compared to pain-free peers.

Methods
Ninety-seven adolescents were enrolled in this study, assessing salivary cortisol at several time points around fear acquisition and extinction in an MRI environment. Data of 89 adolescents could be analyzed (58 patients with chronic pain, 31 controls, mean age 16.1y ± 2.9y, 76 females). Salivary cortisol across time points will be compared across groups.

Results
Preliminary data inspection indicates changes in cortisol over time, especially from pre- to post-extinction. Fear acquisition did not appear to elicit an increase in cortisol. Comparing the Area Under the Curve (AUCg) across groups showed a greater cortisol response in patients compared to controls (patients: mean 319 ± 36; controls: mean 438 ± 60).

Conclusions
We show first preliminary data of physiological stress responses to fear learning. Adolescents with chronic pain appear to show greater stress responses, but further analyses are needed to corroborate and further explore these findings. Findings will impact treatment approaches targeting fear extinction.

PHYSIOLOGICAL STRESS RESPONSES TO FEAR LEARNING IN YOUTH WITH CHRONIC PAIN: SALIVARY CORTISOL ASSESSMENT