The role of the communicated treatment rationale on treatment outcome: study protocol for a randomized controlled trial.

BACKGROUND: Placebo effects are a well-established phenomenon in the treatment of depression. However, the mechanism underlying these effects are not fully understood. Treatment expectations are considered one explanation for why placebos work. Treatment expectations are likely to be affected by clinician-patient interactions. This study aims to investigate the role of the communicated treatment rationale in modulating treatment expectations and its effects on the treatment outcomes of a pharmacological and a psychological active placebo intervention for depression. In this study, treatment expectations are modulated by presenting illness models that are either congruent or incongruent with the treatment intervention that follows. METHODS: This 2 × 2 randomized controlled trial will involve patients with major depression. Participants will either receive a biological or a psychological illness model from a clinician. Following this, they are randomly assigned to receive either a pharmacological or a psychological active placebo intervention. The illness model and the treatment are either congruent or incongruent with each other, resulting in four groups. In addition, a natural course control group will be included. DISCUSSION: This study will provide insights into the mechanism of expectation modulation in active placebo treatments for major depression. The results may provide insights for clinicians to improve their communication with patients by focusing on treatment expectations. By identifying the factors that contribute to placebo effects, this study has the potential to improve the effectiveness of existing depression treatments and reduce the burden of this highly prevalent mental health condition. TRIAL REGISTRATION: This trial has been registered prospectively at ClinicalTrials.gov under the identifier: NCT04719663. Registered on January 22, 2021.

Optimising the efficacy of a stress-reducing psychological intervention using placebo mechanisms: A randomized controlled trial.

This study examined whether i) brief videos aiming to optimise outcome expectations would augment the efficacy of progressive muscle relaxation (PMR) and ii) whether participants' characteristics would moderate these effects. Sixty-eight healthy subjects randomized to one of three experimental manipulations before undergoing a single PMR session either watched i) a video displaying a neutral expert, ii) a video with a warm expert, or iii) were part of an active control condition. Constrained linear mixed models indicated increased relaxation and decreased stress levels for all participants after the PMR session. The primary outcome was the change of perceived relaxation/stress from pre to post. Participants with high neuroticism and trait anxiety indicated an augmented PMR's efficacy and increased outcome expectations when watching the warm expert video compared to the control group or the less warm expert. Brief videos displaying an expert aiming to optimise outcome expectations regarding a brief stress-reducing psychological intervention may boost or decrease an intervention's efficacy. Effects may depend on the viewer's personality and the (video) expert's communication style. Trial Registration: The study protocol was approved by the local Ethics Committee of the University of Marburg, Germany. This study was registered at www.clinicaltrials.gov (NCT03330431).

Does Health Literacy Make a Difference? Comparing the Effect of Conventional Medicine Versus Homeopathic Prescribing on Treatment Credibility and Expectancy.

OBJECTIVE: While homeopathic remedies are often used to treat non-specific complaints such as headaches, empirical evidence suggests their treatment effect is due to the placebo effect. Low health literacy seems to be connected to higher use of complementary and alternative medicine (CAM). The aim of this study was to examine what people with occasional headaches expect from conventional medicine or homeopathic remedies and if health literacy interacts with this expectation. METHODS: In this experimental study, n = 582 participants with occasional headaches were randomized to read one of two vignettes, which described the prescription of either conventional medicine or a homeopathic remedy. Subsequently, the participants were asked to rate treatment credibility and expectancy with regard to their assigned vignette. Health literacy was assessed as a potential moderator. RESULTS: Participants in the conventional medicine group rated treatment credibility and expectancy higher than in the homeopathic remedy group. Moderation analysis revealed that when being offered conventional medicine, participant reports of treatment credibility and expectancy decreased with lower health literacy, while these outcomes increased with lower health literacy for homeopathic remedies. DISCUSSION: People with occasional headaches estimate the effectiveness of conventional medication properly. However, health care professionals should pay special attention to patients with low health literacy, as they might need more time and information to give their informed consent.