EMDR Versus Imagery Rescripting for Trauma-Related Intrusions

The goal of this clinical trial is to investigate the effectiveness and mechanisms of action of trauma treatments in a sample of patients meeting criteria for posttraumatic stress disorder (PTSD), unipolar depression, or both disorders. The main questions it aims to answer are:

* which first line treatment (Eye Movement Desensitization and Reprocessing \[EMDR\] vs. Imaginary Rescripting \[IR\]) works better for intrusive experiences in patients with PTSD, patients with a depression, and patients who meet criteria for both diagnoses.
* which mechanisms of action cause the treatment effects.

Participants will

* be randomly assigned to a standard treatment of EMDR or IR
* complete daily questionnaires measuring the outcome measures two weeks before the start of their treatment, during their EMDR or IR treatment, and for one month after their treatment.
* complete questionnaires measuring the outcome measures and secondary outcome measures at pre-intervention, post-treatment (i.e., 4 weeks after the last intervention session, at the end of the withdrawal phase), and at 6-month follow-up.

Rationale: Patients with post-traumatic stress disorder (PTSD) experience highly frequent and distressing intrusive images depicting earlier aversive experiences. Not only patients with PTSD experience these intrusions; they are also very common in depression. Therefore, trauma treatments that target these intrusions may also benefit patients with depression. Additionally, comorbid depression in patients with PTSD reduces the effects of trauma treatment. It is currently unknown which treatment for traumatic intrusions is most effective for patients who meet criteria for PTSD, depression, or both, and treatment selection is often a process of trial and error. The mechanisms of action of trauma treatments may inform us how to select the most appropriate treatment for a particular individual.

Objective:

The investigators' primary objective is to investigate which treatment (EMDR vs. IR) is most effective for different groups of patients who experience intrusions: patients with PTSD, patients with depression, or patients with PTSD and a comorbid depression. To this end, the investigators will examine the reduction in the severity of intrusions (i.e., frequency, uncontrollability, and degree of interference with daily life). The investigators' secondary objective is to gain more insight into the mechanisms of action of EMDR and IR. To this end, the investigators will examine the role of various mediators of the treatment effects (i.e., the reduction in the severity of intrusions). The investigators will specifically investigate the potential mediating roles of self-compassion, emotion regulation, positive affect, rumination, and the vividness, distress, and associated meaning of intrusions.

Study design: This study will use a single-case experimental design (SCED). In this design, a small group of patients is followed throughout their treatment. It is a within-subjects design in which each patient undergoes a baseline phase (2 weeks prior to the start of treatment) in which no intervention takes place, an experimental phase with treatment interventions (at least 2.5 weeks), and finally a withdrawal phase (4 weeks following the last intervention session) in which no further treatment takes place.

Study population: This study will recruit 42 patients meeting criteria for either PTSD or depression, or for both disorders.

Intervention (if applicable): Patients will be randomly assigned to standard treatments EMDR or IR. In each condition, patients will receive two 75-minute sessions of EMDR or IR each week, as well as an additional coaching session each week. Treatment length depends on patients' needs and varies between 2.5 and 6 weeks.

Main study parameters/endpoints: The primary outcome is a brief measure of characteristics of intrusions (specifically, the frequency, uncontrollability, and degree of interference with daily life), which will be assessed twice daily via an online mobile app.

Additionally, process measures indexing possible mediators concern brief questionnaires on emotion regulation, self-compassion, rumination, positive affect, and the vividness, distress, and related meaning of intrusions, which also serve as the investigators' primary outcome measures. These questionnaires will be assessed daily. All primary outcome measures will be administered during the baseline, experimental, and withdrawal phase. Secondary outcome measures concern questionnaires on quality of life, depression symptoms, and PTSD symptoms which are endorsed at the pre-intervention assessment (i.e., 2 weeks prior to the first intervention session), post-treatment assessment (i.e., 4 weeks after the last intervention session, at the end of the withdrawal phase), and at 6-month follow-up assessment.

Eligibility Criteria:
Inclusion Criteria:

* age between 18 and 70 years
* experiencing intrusions and/or nightmares
* meet criteria for unipolar depressive disorder, PTSD, or both disorders
* past aversive events still cause considerable distress
* be available for trauma treatment twice a week, with an additional coaching session each week
* be proficient in the Dutch language.

Exclusion Criteria:

* the presence of a dissociative identity disorder
* acute suicide risk
* acute psychosis
* substance use disorder
* bipolar disorder type 1 and 2. Other comorbid disorders are allowed.