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ID
Source
Brief title
Health condition
Healthy participants
Sponsors and support
Intervention
Outcome measures
Primary outcome
Generalization of placebo and nocebo effects to pressure pain. Following the heat pain conditioning and test, participants will receive 6 medium pressure pain stimuli; 3 stimuli with ENS ‘ON’ and 3 with ENS ‘OFF’. After each stimulus, participants will be asked to rate their pain intensity by using a 0-10 numerical rating scale. Our primary outcome is the comparison of the difference in average pressure pain between ENS ‘ON’ and ‘OFF’ in placebo and nocebo groups, respectively. Additionally, maximum pressure pain ratings between ENS ‘ON’ and ‘OFF’ in these groups will also be compared.
Secondary outcome
Generalization of placebo and nocebo effects to cowhage-evoked itch. Following the heat pain conditioning, participants will receive cowhage twice, once with ENS ‘ON’ and once with ENS ‘OFF’. As soon as participants feel itch for the first time, they will be asked to rate their itch intensity by using a 0-10 numerical rating scale every 10 seconds for 3 minutes. Our primary outcome is the comparison of the difference in average itch ratings between ENS ‘ON’ and ‘OFF’ in placebo and nocebo groups. Additionally, maximum itch ratings between ENS ‘ON’ and ‘OFF’ in these groups will also be compared.
Psychological factors: the individual characteristics (e.g.,, anxiety) will be used to investigate possible moderators of placebo and nocebo effects within and across modalities.
Background summary
In this study on healthy participants, we are investigating whether placebo and nocebo effects on pain can generalize to another type of pain and to itch. Placebo and nocebo effects will be induced by combining verbal suggestion (by telling the participant that the sensation will decrease/increase) with conditioning with heat pain (by actual changes in the stimulus intensity of induced heat pain). To test generalization, pressure pain stimuli will be applied during six trials; three with a control cue and three with a conditioned cue. Moreover, cowhage-evoked itch will be applied twice, once with a control cue and once with a conditioned cue. This study uses a within-subjects design, pain/itch ratings with the conditioned cue will be compared with the control cue in the placebo and nocebo group, respectively.
Study objective
1.The primary objective of this study is to test whether placebo and nocebo effects generalize within pain stimulus modalities, i.e. from heat pain to pressure pain.
2.The secondary objective of this study is to test whether placebo and nocebo effects generalize across somatosensory modalities, i.e., from heat pain to cowhage-evoked itch.
3.The exploratory objective of this study is to explore the role of individual characteristics variables (i.e., anxiety and depression; stress; attention to pain and itch; optimism and pessimism; pain catastrophizing; itch catastrophizing) in the generalization of placebo and nocebo effects within pain stimulus modalities and from pain to itch.
Study design
The whole experiment will take around 2 hours and 30 minutes per participant in a single session.
Intervention
Participants will learn the links between the changes of heat pain intensity with an Electrical Nerve Stimulation (ENS) device ‘ON/OFF’. This ENS device serves as a sham device and does not work in the main test. In the placebo group, participants will be told that ENS ‘ON’
means a decrease of heat pain (a conditioned cue) and ENS ‘OFF’ means no change of heat pain (a control cue). In fact, participants will receive low heat pain with ENS ‘ON’ and medium heat pain with ENS ‘OFF’ during the learning phase. In the nocebo group, participants will be told that ENS ‘ON’ means an increase of heat pain (a conditioned cue) and ENS ‘OFF’ means no change of heat pain (a control cue). In fact, participants will receive high heat pain with ENS ‘ON’ and medium heat pain with ENS ‘OFF’ during the learning phase.
Inclusion criteria
1. Healthy participants between 18 and 35 years old;
2. Fluent in the English language.
Exclusion criteria
1.Refusal to give written informed consent
2.Severe morbidity (e.g., multiple sclerosis, heart or lung disease, chronic itch or pain complaints)
3.DSM-IV psychiatric disorders (e.g., depression, autism)
4.Regular use of recreational drugs
5.Current use of medication
6.Pregnancy or lactation
Design
Recruitment
IPD sharing statement
Plan description
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In other registers
| Register | ID |
|---|---|
| NTR-new | NL8072 |
| Other | Psychology Ethics Committee Leiden University : CEP18-1218/491 |