Benefit of placebo effects in atopic dermatitis - Increase of the pharmacological effects in itching via processes of conditioning and expectation

• Applicants: Privatdozentin Dr. Regine Klinger; Professorin Dr. Margitta Worm
• Subject Area: Personality Psychology, Clinical and Medical Psychology, Methodology ; Dermatology
• Term: from 2012 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 230647828

The empiric efficacy of placebo is widely accepted: Pain can be reduced by placebo. As comparable neurophysiologic processes are involved in the transmission of pain and itch, the concept of placebo mediated clinical efficacy might also be relevant for itch. This is of particular importance since itch is still difficult to treat. Antihistamines and corticosteroids belong to the frequently used drugs in atopic dermatitis, however they display limitations regarding their clinical efficacy. The main goal of this study is to answer the question whether placebo effects can enhance the pharmacological efficacy of antipruritic drugs in patients suffering from a chronic skin disease, which is typically associated with itch (atopic dermatitis). In our model we use exemplarily histamine induced itch which is then treated with antihistamines. The following questions should be answered by our experimental setting: 1.) Can the perception of itch be altered by specific instructions which expectancy the variance of antihistamine efficacy can be explained via physiological variables (placebo effects)? 2.) A pharmacologic free infusion (sodium chloride 0,9 %) which is introduced by using specific instructions. These build up expectancy and which will be coupled with defined learning conditions by classical conditioning. 3.) Is it possible to retain the placebo effect over time?To address these questions our randomized groups will be build (open hidden design, 124 AD patients). The independent variables (drug, instruction and conditioning) are assessed at two different examination time points. The primary dependent variable in each group is the subjective assessment of itch by the patient, as secondary parameters objective variables (like Regine?) will be determined.The results will unravel the role and mechanisms of placebo efficacy in an itch model and build the basis to develop novel innovative treatment concepts.

• DFG Programme: Research Grants