Posttraumatic stress disorder (PTSD) is a frequently occurring and often debilitating anxiety disorder resulting from exposure to trauma. Trauma-focused cognitive-behavioural therapies, such as Eye movement desensitization and reprocessing (EMDR), are generally considered to be evidence-based treatments for PTSD. Although a majority of patients achieve improvement, a substantial minority either drop out of treatment, present with residual symptoms following treatment or fail to make any improvement. Furthermore, a substantial portion of the clinical trials on PTSD is characterised by major methodological limitations. In addition, there's a pressing need for research on mediators of treatment outcome. Taken together, these results highlight the need for methodological rigorous and stringent clinical trials comparing treatment modalities for PTSD. The first aim of this study is to investigate whether a treatment not based on the principles of exposure, i.e. metacognitive therapy (MCT) is as efficient as exposure-based treatments. The second aim to elucidate potential mediators of treatments effects by incorporating process-related variables.

EMDR is based on the assumption that posttraumatic symptoms are due to the traumatic experience(s) being stored in an unprocessed way disconnected from existing memory networks. The procedure in EMDR is postulated to facilitate the processing of the traumatic memory into existing memory networks. There is currently no empirical knowledge as to the therapeutic mechanisms of EMDR, but the protocol overlaps with core components of cognitive behavior therapy (CBT), such as imaginal exposure and cognitive restructuring of negative trauma-related cognitions. Thus, EMDR could be viewed as a form of CBT, although its originator maintains that it is a distinct treatment. EMDR is usually considered an evidence-based treatment of PTSD.

MCT is one of the new approaches in the treatment of PTSD. The metacognitive model posits that adaptation following exposure to trauma depends on metacognitive beliefs that guide how the individual interprets and responds to posttraumatic symptoms and can lead to styles of thinking that facilitate or impede emotional processing. MCT focuses on "unlocking" or removing the barriers to natural adaptation. This equips the client with general skills and therefore protects the individual from the risk of any future re-traumatisation. In contrast to EMDR, MCT does not involve proscribed exposure exercises or restructuring of negative trauma-related cognitions.

In addition we will include a group of 30 patients matched for age, gender and personality disorders receiving treatment as usual (TaU) in an outpatient setting as a non-randomized comparative control condition.

Inclusion Criteria:

• a primary diagnosis of PTSD according to the Anxiety Disorders Interview Schedule (ADIS-IV)
• not previously received EMDR or MCT for this diagnosis
• not actively suicidal, presenting with suicidal ideation, psychotic or suffering from severe depression
• no evidence of alcohol or drug dependence
• Symptom chronicity of >3 months post-trauma

Exclusion Criteria:

• PTSD is not the primary diagnosis
• expressing suicidal ideation, actively psychotic, or engaging in overt self-harm
• Evidence of alcohol or drug dependence requiring treatment in its own right
• Borderline personality disorder
• Symptom chronicity <3 months post-trauma
• no ability to understand or speak Norwegian