Healthy participants
Conditions
Interventions
Conditioning: Participants will undergo a conditioning paradigm acquisition phase consisting of four cowhage administrations. A verbal suggestion is made, informing participants that one of two cream
Sponsors
Leiden University, Leiden, the Netherlands
Eligibility
Inclusion criteria
Inclusion criteria: Female Age 17-35 Good understanding of written and spoken English
Exclusion criteria
Exclusion criteria: Have current or a history of chronic / recurring dermatological conditions. Have current physical or mental illness. Currently take medication for the management of pain or itch symptoms. Have injuries on the hands, wrists, or arms at the time of participation. Are pregnant or breastfeeding. Are colorblind.
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Nocebo effect on itch: Following one of the three previously described interventions, participants in all groups will complete an identical test phase of two cowhage administrations, one following administration of the nocebo cream and one without. Both test phase trials will use the same low cowhage dose as used in the control trials of the learning phase. The order of these two trials will be randomized so that half of participants in each group receive the nocebo cream on their first trial, and half on the second trial. The same administration and itch rating procedures as described in the learning phase administrations will be used in the test phase. During each trial participants are asked to rate their itch on a 0-100 scale every 15 seconds for 3 minutes, starting 15 seconds after the first report of feeling itch following administration of the cowhage. The nocebo effect is then measured as the difference in average itch ratings between the nocebo associated trial and the control trial of the test phase. Our primary outcome is the comparison of this difference (the nocebo effect) between the active conditioning and sham conditioning groups, and between the observational learning and sham conditioning groups. | — |
Secondary
| Measure | Time frame |
|---|---|
| Observational learning: Our first secondary outcome is the comparison of the difference in average itch ratings between the nocebo associated trial and the control trial of the test phase (the nocebo effect) between the observational learning and sham conditioning groups. Scratching behavior: Video recording of the participant’s lab session will be collected with the participant’s consent, and used to analyze the frequency and duration of scratching behavior during the experiment. Psychological factors: Questionnaire measures of empathy (Interpersonal Reactivity Index; Pulos, Elison, & Lennon, 2004), state anxiety (Spielburger State Anxiety Inventory; Marteau & Bekker, 1992), social desirability (Marlow-Crowne Social Desirability Scale; Crowne & Marlow, 1960), mindfulness (Five Factor Mindfulness Questionnaire; Tran, Gluck, & Nader, 2013), stress (Perceived Stress Scale; (Cohen, Kamarck, & Mermelstein, 1983), mood (Positive and Negative Affect Scale; Watson, Clark, & Tellegen, 1988) and sleep quality (Sleep Condition Indicator; Espie et al., 2014) will be used to investigate possible moderators of nocebo effects on itch as a secondary, exploratory analysis. | — |
Contacts
Public ContactAndrea Evers
Leiden University
Outcome results
None listed