Pain and Itch Neuromodulation: Effects of Offset Analgesia, Placebo, and Nocebo and Topographical Distribution of Itch and Pain Receptors

What this Trial Is About

Researchers are investigating how the placebo effect influences itch and pain sensations, particularly those caused by histaminergic and non-histaminergic triggers. This study includes healthy adults aged 18 to 60 and examines the relationship between these sensations and personality traits like depression, anxiety, and stress. The research is conducted by Aalborg University and focuses on understanding neuromodulation mechanisms involving pain and itch perception. During the approximately 1.5-hour experimental session, participants complete questionnaires about their perceptions of itch and pain, along with assessments of personality traits. Four areas on the volar forearms are treated with a placebo cream for 20 minutes to test the placebo effect. Afterward, two areas are randomly exposed to histamine using allergy skin prick test lancets, while cowhage spicules are applied to the other two areas. Itch and pain levels are continuously monitored for 10 minutes using a Visual Analog Scale. Participants are involved in one study session where they fill out several baseline questionnaires related to pain and itch catastrophizing, emotional regulation, and personality. During and immediately after the application of creams and pruritogens, pain and itch are measured using computerized Visual Analog Scales. The study monitors responses to assess neuromodulation effects without any masking or blinding. The entire participation includes baseline assessments and immediate measurements following interventions within a single visit.

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