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

Philipps University

Status: Completed

Conditions: Condition: Major Depressive Disorder (MDD)

Treatments: Behavioral: Active psychological placebo; Behavioral: Psychological illness and treatment rationale; Behavioral: Biological illness and treatment rationale; Drug: Active pharmacological placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT04719663

CRC 289 Project A16

Details and patient eligibility

About

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.

Enrollment: 150 patients

Sex: All

Ages: 18 to 80 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Diagnosis of major depression according to the 'Structured Clinical Interview for DSM-V' (SCID)
• Age>17
• Comorbidity is allowed if major depression is the dominant clinical problem
• Concordant medication is allowed if kept constant for the four weeks before and until the end of the trial (with the exception of benzodiazepines and if not contraindicated together with Buscopan)
• Fluency in German
• Informed consent

Exclusion criteria

• Severe depression (BDI> 30) or suicidality
• Psychosis
• Significant neurological diseases
• Other mental or physical disorder with substantial influence on disability
• Benzodiazepine intake
• Any intolerance against Buscopan and sucrose or any medical condition/treatment conflicting with Buscopan intake

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

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150 participants in 5 patient groups

1. Congruent Rationale & Treatment: Biological/Pharmacol.

Experimental group

Description:

Participants receive a biological illness explanation and treatment rationale. During treatment they receive a placebo pill (Buscopan).

Treatment:

Behavioral: Biological illness and treatment rationale

Drug: Active pharmacological placebo

2. Incongruent Rationale & Treatment: Psychological/Pharmacol.

Experimental group

Description:

Participants receive a psychological illness explanation and treatment rationale. During treatment they receive a placebo pill (Buscopan).

Treatment:

Behavioral: Psychological illness and treatment rationale

Drug: Active pharmacological placebo

3. Congruent Rationale & Treatment: Psychological/Psychol.

Experimental group

Description:

Participants receive a psychological illness explanation and treatment rationale. During treatment they receive a placebo psychological treatment (emotional writing).

Treatment:

Behavioral: Psychological illness and treatment rationale

Behavioral: Active psychological placebo

4. Incongruent Rationale & Treatment: Biological/Psychol.

Experimental group

Description:

Participants receive a biological illness explanation and treatment rationale. During treatment they receive a placebo psychological treatment (emotional writing).

Treatment:

Behavioral: Active psychological placebo

Behavioral: Biological illness and treatment rationale

5. Natural course control

No Intervention group

Description:

Participants receive no intervention and remain on the psychotherapy waiting list. Participants who are recruited externally and are not on a waiting list, will be offered the option to join the waiting list.