Negative Expectancies, but not Stress, are Predictive of Cowhage-induced Itch Ratings and Urge to Scratch in a Healthy Population

Background: Itch and scratching are distressing symptoms in diverse diseases. Both negative expectancies and stress have been shown to increase symptom severity. However, especially the role of stress remains unclear as it has mostly been tested in pain studies. Methods: To investigate whether the effect of stress on itch is mediated by negative expectancies; cowhage, verbal suggestions and a video fragment were used to induce itch in a within-subjects design of 11 healthy participants. Itch, scratching and negative expectancies were measured on a scale from 0 to 10. Stress was assessed by the DASS-21 questionnaire. Results: Using mediation analysis, results suggested that stress was not predictive of itch symptoms at all, even when taking into account negative expectancies. Nonetheless, negative expectancies on their own were related to itch and scratching. Conclusions: These findings demonstrate that negative expectancies should be treated as a key aspect in psychological...Show moreBackground: Itch and scratching are distressing symptoms in diverse diseases. Both negative expectancies and stress have been shown to increase symptom severity. However, especially the role of stress remains unclear as it has mostly been tested in pain studies. Methods: To investigate whether the effect of stress on itch is mediated by negative expectancies; cowhage, verbal suggestions and a video fragment were used to induce itch in a within-subjects design of 11 healthy participants. Itch, scratching and negative expectancies were measured on a scale from 0 to 10. Stress was assessed by the DASS-21 questionnaire. Results: Using mediation analysis, results suggested that stress was not predictive of itch symptoms at all, even when taking into account negative expectancies. Nonetheless, negative expectancies on their own were related to itch and scratching. Conclusions: These findings demonstrate that negative expectancies should be treated as a key aspect in psychological treatment targeting chronic pruritus, such as rational-emotive therapy (RET). However, future research should still investigate stress in relation to itch, as the current study did not assess the impact of severe stress levels and experimentally-induced stress.Show less

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Negative Expectancies, but not Stress, are Predictive of Cowhage-induced Itch Ratings and Urge to Scratch in a Healthy Population