The Modulatory Role of Communicated Treatment Rationale on Treatment Expectation Effects in Depression.

Summary

Placebo groups in clinical trials on depression show impressive improvements. Yet, there is little research on the mechanism underlying this effect. The aim of this study is to assess how patients' treatment expectations modulate the placebo treatment effects.

We expect that patients' treatment expectation determines placebo responses and treatment outcomes, and that this expectation is influenced by the disorder explanations (information about the illness models) typically provided during the initial medical encounters that precede treatment.

In the study we aim to manipulate depressed patients' expectations by providing two different clinician-delivered illness and treatment rationales (biological/ psychological). Patients will then receive placebo treatment (pharmacological/ psychological), that is either congruent or incongruent with the previously communicated treatment rationale.

Hypotheses:

1. Providing a treatment-congruent treatment rationale leads to a better outcome than providing treatment-incongruent rationales.
2. Treatment-congruent explanations reduce the risk of side effect development, in particular in the medication arm.
3. Inter-individual differences in the effect of provided treatment rationale are associated with pre-treatment experiences and expectations, depression severity and comorbid anxiety.

Conditions

• Condition: Major Depressive Disorder (MDD)

Interventions

BEHAVIORAL

Biological illness and treatment rationale

Depression is described as a brain disorder and the role of monoamine, brain structures, and brain functions are reported as central mechanisms of relevance for its etiology and treatment. Biological processes are illustrated using typical charts and visualizations. Psychological influences are mentioned, but only as a byproduct of the disorder.

BEHAVIORAL

Psychological illness and treatment rationale

Depression is described as a psychological disorder resulting from emotion regulation deficits. The suppression of emotions receives a special role in explaining depression. The psychological processes are illustrated using charts and visualizations. Biological aspects are mentioned, but only as a byproduct of the disorder.

DRUG

Active pharmacological placebo

The active placebo pill does not have direct effects on the brain. Buscopan (butylscopolamine, 10 mg daily, 1 pill in the morning) does not cross the blood-brain barrier, yet induces some smaller side effects that resemble those of antidepressants (e.g., mouth dryness, fatigue, nausea). Treatment duration is 4 weeks. The rationale is briefly explained to participants as "stimulating the biological balance in humans with depression, using a well-tolerated drug similar to Buscopan, which is well-known from pain treatments.

BEHAVIORAL

Active psychological placebo

"Emotional writing" consists of writing about emotional experiences (4 sessions, one per week, 30 minutes each). The study instructor will be present displaying standard psychotherapeutic attitudes but will not read the participant's notes. The rationale for this treatment is briefly explained as "improving the dealing" with emotions to achieve a psychological balance in humans with depression.

Sponsors & Collaborators

• Psychotherapie-Ambulanz Marburg e.V.

  collaborator OTHER

• Philipps University Marburg

  lead OTHER

Principal Investigators

• Winfried Rief · Philipps University Marburg

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

80 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2021-04-13

Primary Completion

2023-09-12

Completion

2023-09-12

Countries

• Germany

Study Locations