Targeted Use of Placebo Effects Decreases Experimental Itch in Atopic Dermatitis Patients: A Randomized Controlled Trial

Evidence from pain research shows that the effectiveness of active pharmacological treatments can be enhanced by placebo effects. The "open drug administration" is superior to "hidden drug administration.​" In a randomized controlled trial, we aimed to show that the targeted use of placebo effects increases the efficacy of an antihistamine (dimetindene) infusion in participants with atopic dermatitis. We openly infused dimetindene (drug) in full sight with information (intervention group 1: OPEN-DRUG+INST), openly infused drug with an additional classical conditioning learning experience (intervention group 2: OPEN-DRUG+INST+COND) or infused drug without any information or sight (i.e., hidden administration (control group 1: HIDDEN-DRUG)). Control group 2 received a placebo infusion (saline) declared as dimetindene and also experienced the conditioning experience (PLAC+INST+COND). Itch was experimentally induced with histamine via a skin prick test. Outcome was assessed at the subjective (primary end point: experimental itch intensity, numeric rating scale), and objective level (secondary end point: wheal size, mm² ). Experimental-induced itch intensity decreased in all groups but at different rates (P < 0.001). The groups with the open administration, whether it was dimetindene or placebo, had significantly stronger reductions in itch compared to the HIDDEN-DRUG group (OPEN-DRUG+INST+COND: P < 0.001; OPEN-DRUG+INST: P = 0.009; and PLAC+INST+COND: P < 0.001). Additional drug conditioning mediated via expectation led to a stronger reduction of itching (P = 0.001). Results on wheal size were similar (P = 0.048), however, no significant difference between the HIDDEN-DRUG group and the PLAC+INST+COND group (P = 0.967) was found. We conclude that specifically generated targeted placebo effects can significantly increase the action of a drug (dimetindene) and should be used in clinical practice.

Biofeedback-based self-alert training reduces alpha activity and stabilizes accuracy in the Sustained Attention to Response Task

OBJECTIVE

Deficits in sustaining attention are common in various organic brain diseases. A recent study proposed self-alert training (SAT) as a technique to improve sustained attention. In the SAT, individuals learn to gain volitional control over their own state of arousal by means of electrodermal biofeedback.

METHOD

In this study, we investigated the behavioral, electrodermal, and electroencephalogram correlates of the SAT with a blinded, randomized, and active-controlled pre-post study design. Sustained attention capacity was assessed with the Sustained Attention to Response Task (SART).

RESULTS

The SAT resulted in strong phasic increases in skin conductance response (SCR), but endogenous control of SCR without feedback was problematic. Electroencephalogram analysis revealed stronger alpha reduction during SART for the SAT than for the control group. Behaviorally, the SAT group performed more accurately and more slowly after intervention than the control group.

CONCLUSION

The study provides further evidence that SAT helps to maintain SART accuracy over prolonged periods of time. Whether this accuracy is more related to sustained attention or response inhibition is discussed.

How to Psychologically Minimize Scratching Impulses

Research in recent years, especially in the analgesic field, has intensively studied the placebo effect and its mechanisms. It has been shown that physical complaints can be efficiently reduced via learning and cognitive processes (conditioning and expectancies). However, despite evidence demonstrating a large variety of physiological similarities between pain and itch, the possible transfer of the analgesic placebo model to itch has not yet been widely discussed in research. This review therefore aims at highlighting potential transfers of placebo mechanisms to itch processes by demonstrating the therapeutic issues in pharmacological treatments for pruritus on a physiological basis and by discussing the impact of psychological mechanisms and psychological factors influencing itch sensations.