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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
150
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.
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.
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.
"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.
Department of Clinical Psychology and Psychotherapy, Philipps-University Marburg
Marburg, Germany
Change in depression severity scores after 4 weeks of treatment - 'Montgomery Asberg Depression Scale' (MADRS)
Expert rating to assess depression severity; 10 items; each item is rated on a 7-point scale (0-6); total scores range between 0-60 (higher scores indicate more severe depression)
Time frame: Baseline, post-treatment (4 weeks after start of treatment)
Change in depressive symptom scores after 4 weeks of treatment- 'Beck Depression Inventory' (BDI-II)
Self-report questionnaire to assess subjective depression symptomatology; 21 items (each item response is scored 0-3); total scores range from 0 - 63 (higher scores indicate more depressiveness)
Time frame: Baseline, post-treatment (4 weeks after start of treatment), and at follow-up (1 week later)
Change in subjective disability scores after 4 weeks of treatment - adaptation of 'Pain Disability Index' (PDI)
Self-report questionnaire to assess illness burden; 7 items; each item rated on a 0 (no disability)-10(maximum disability) standardized numerical analogue scale; total scores range from 0-70 (higher scores indicate more disability)
Time frame: Pre-treatment (2-7 days after baseline), post-treatment (4 weeks after start of treatment), and at follow-up (1 week later)
Change in 'Generic Assessment of Side-Effects' scores (GASE) after 4 weeks of treatment
Self-report questionnaire to assess experience of side effects; 36 items; each item describes a side-effect symptom which is rated on a 4-point scale from 0 (not present)-3 (strong experience); total scores range from 0-108 (higher scores indicate stronger experience of side effects)
Time frame: Pre-treatment (2-7 days after baseline), post-treatment (4 weeks after start of treatment), and at follow-up (1 week later)
Change in treatment expectations at the start of treatment - 'Treatment Expectation Questionnaire' (TEX-Q)
Self-report questionnaire to assess expectations about treatment outcomes; 15 items; each rated on a 0 (no expectation of improvement)- 10(most improvement imaginable) numeric scale; total scores range from 0-150 (higher scores indicate better treatment expectations)
Time frame: Baseline, pre-treatment (2-7 days after baseline)
Change in subjective stress scores after 4 weeks of treatment - 'Perceived Stress Scale' (PSS-10)
Self-report questionnaire to assess subjective stress experience; 10 items; each item is rated on a 5-point scale from 0(never) to 4(very often); total scores range between 0 and 40 (higher scores indicate more subjective stress)
Time frame: pre-treatment (2-7 days after baseline), post-treatment (4 weeks after start of treatment), and at follow-up (1 week later)
Change in anxiety scores after 4 weeks of treatment - 'State-Trait-Anxiety- Depression-Inventory' (STADI)
Self-report questionnaire to assess state and trait anxiety and depression; 40 (20 state scale; 20 trait scale) items; each item is rated on a 4-point scale from 1(not at all) to 4(very much); total scores per scale range between 20 and 80 (higher scores indicate more anxiety)
Time frame: State scale: Baseline; pre-treatment (2-7 days after baseline), post-treatment (4 weeks after start of treatment) and at follow-up (1 week later); Trait scale only measured at baseline
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