Mechanisms Underlying the Placebo Effect in Both Histaminergic and Non-histaminergic Itch

Aalborg University30 enrolled

Overview

The study consists of one experimental session of approximately 1½ hours. The participant will fill in a series of questionnaires about how you perceive itch and pain, and about some traits of your personality, such as depression, anxiety and stress. Afterwards, two areas will be selected on each forearm of the subjects. The four areas will be treated with the same vehicle cream for 20 minutes, in order to test the placebo effect. At the end of the cream application, two areas will be randomly treated with histamine while cowhage will be applied on the other two areas. During the 10 minutes of the application of the pruritogens, itch and pain will be continuously monitored using a Visual Analog Scale.

Study Type

INTERVENTIONAL

Allocation

Purpose

BASIC_SCIENCE

Masking

NONE

Enrollment

Conditions

ITCH

Interventions

Eligibility

Sex: ALLMin age: 18 YearsMax age: 60 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Healthy men and women * 18-60 years * Speak and understand English Exclusion Criteria: * Pregnancy or lactation * Drug addiction defined as any use of cannabis, opioids, or other drugs * Previous or current history of neurological, immunological, musculoskeletal, cardiac disorder or psychiatric diagnoses that may affect the results (e.g., neuropathy, muscular pain in the upper extremities, anxiety, depression, schizophrenia, etc.) * Moles, wounds, scars, or tattoos in the area to be treated or tested * Current use of medications that may affect the trial such as antihistamines and pain killers * Skin diseases * Consumption of alcohol or painkillers 24 hours before the study days and between these * Acute or chronic pain and itch * Participation in other trials within 1 week of study entry (4 weeks in the case of pharmaceutical studies) * Contraindications to capsaicin, including intolerance to chili or burns or wounds at the application site * The subject is assessed as unable to engage in the necessary cooperation required by the study

Outcomes

Primary Outcomes

Measuring pain by computerized Visual Analog Scale Scoring

We will ask the subjects to rate the sensation of pain on a 100 mm Visual Analog Scale ranging from 0 to 100 where 0 indicates" no pain" and 100 indicates "worst pain imaginable".

Time frame: Immediately after the intervention

Measuring itch by computerized Visual Analog Scale Scoring

We will ask the subjects to rate the sensation of itch on a 100 mm Visual Analog Scale ranging from 0 to 100 where 0 indicates "no itch" and 100 indicates "worst itch imaginable".

Time frame: Immediately after the intervention

Secondary Outcomes

Pain Catastrophizing Scale (PCS).

The PCS assesses negative and exaggerated coping concerning anticipated or experienced painful stimuli. Thirteen items have to be answered on a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (all the time).

Time frame: Baseline

Itch Catastrophizing Scale (ICS).

The ICS assesses negative and exaggerated coping concerning anticipated or experienced itchy stimuli. Thirteen items have to be answered on a 5-point Likert-type scale ranging from 0 (Not at all) to 4 (all the time).

Time frame: Baseline

Learned Helplessness Scale (LHS)

The questionnaire consists of 20 items, and the participant's response to each item is rated on a 4-point Likert scale ranging from strongly agree (1) to strongly disagree (4).

Time frame: Baseline

Depression, Anxiety, Stress Scale (DASS-21)

The questionnaire measures the magnitude of depression, anxiety, and stress. Each of these three subscales consists of 7 questions answered using a 0-3 Likert scale, with 0 meaning "it did not apply to me", and 3 meaning "it applied to me very much"

Time frame: Baseline

Reinforcement Sensitivity Theory - Personality Questionnaire (RST-PQ).

The RST-PQ contains in total 65 items must be answered on a Response scale: 4-point Likert (Strongly disagree → Strongly agree).

Time frame: Baseline

Positive And Negative Affect Schedule (PANAS)

Twenty words are associated with the subject's current feelings and have to be rated on a 5-points Likert-type scale from: Very slightly or not at all to extremely.

Time frame: Baseline

Difficulties in Emotion Regulation Scale Short Form (DERS-SF)

The questionnaire is an 18-item measure used to identify emotional regulation issues in adults. Participants rate each item on a 5-point Likert scale (from 1 to 5).

Time frame: Baseline

Emotion Regulation Questionnaire (ERQ

This questionnaire is designed to assess individual differences in the habitual use of two emotion regulation strategies: cognitive reappraisal and expressive suppression. Respondents answer each item on a 7-point Likert-type scale ranging from 1 (strongly disagree) to 7 (strongly agree), where 4 means (neutral).

Time frame: Baseline

Mechanisms Underlying the Placebo Effect in Both Histaminergic and Non-histaminergic Itch

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes

Central Contacts