PSYCHOLOGY, PSYCHIATRY & BRAIN NEUROSCIENCE SECTION Original Research Article Individual Modulation of Pain Sensitivity under Stress

Objectives. Stress has a strong influence on pain sensitivity. However, the direction of this influence is unclear. Recent studies reported both decreased and increased pain sensitivities under stress, and one hypothesis is that interindividual differences account for these differences. The aim of our study was to investigate the effect of stress on individual pain sensitivity in a relatively large female sample. Methods. Eighty female participants were included. Pain thresholds and temporal summation of pain were tested before and after stress, which was induced by the Mannheim Multicomponent Stress Test. In an independent sample of 20 women, correlation coefficients between 0.45 and 0.89 indi- cated relatively high test-retest reliability for pain measurements. Results. On average, there were significant differ- encesbetweenpainthresholdsundernon-stressand stressconditions,indicatinganincreasedsensitivity to pain under stress. No significant differences between non-stress and stress conditions were found for temporal summation of pain. On an individual basis, both decreased and increased pain sensitivities under stress conditions based on Jacobson's criteria for reliable change were observed. Furthermore, we found significant nega- tiveassociationsbetweenpainsensitivityundernon- stress conditions and individual change of pain sensitivity under stress. Participants with relatively high pain sensitivity under non-stress conditions became less sensitive under stress and vice versa. Discussion. These findings support the view that pain sensitivity under stress shows large interindi- vidual variability, and point to a possible dichotomy of altered pain sensitivity under stress.