Author: Rie Kubota
Kubota, Rie, 2016 The Role of Rumination on Posttraumatic Intrusions: An Investigation Using the Trauma-film Paradigm, Flinders University, School of Psychology
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Trauma-related rumination, a repetitive and recurrent thinking about the trauma and its meaning, is thought to contribute to the maintenance of posttraumatic stress disorder (PTSD) (e.g., Ehlers & Clark, 2000). The role of trauma-related rumination in PTSD seems particularly relevant to individuals with concurrent depression, for whom rumination is a common cognitive characteristic. Further, depression is theorised to inhibit optimal posttrauma adjustment, and trauma-related rumination may be one cognitive process underlying how depression maintains PTSD. However the causal effects of depression and trauma-related rumination on the symptoms of PTSD have not been established conclusively, nor has trauma-related rumination been explicitly examined as a mediator for the relationship between depression and PTSD. If trauma-related rumination does affect PTSD, interventions that decrease trauma-related rumination may benefit individuals with PTSD. Interventions that include mindfulness techniques may assist in this process but this has not been tested in controlled experimental conditions. Accordingly, using a trauma film paradigm, this thesis examined whether depression and trauma-related rumination causes the maintenance of trauma intrusions, a hallmark symptom of PTSD, and whether trauma-related rumination mediates the predicted effects of depression and/or mindfulness on trauma intrusions. Study 1 examined whether induced low mood would maintain trauma intrusions and associated distress, and whether trauma-related rumination would mediate the relationship between induced low mood or naturally occurring depressive symptoms and trauma intrusions. No evidence was found for a causal role of temporary low mood on the intrusion maintenance; however, trauma-related rumination was found to mediate the effect of naturally occurring depressive symptoms on trauma intrusions. Study 2 built upon the mediation finding from Study 1 by using a pre-selected sample high or low in dysphoria. However, it failed to replicate the findings of Study 1. Studies 3 and 4 tested the causal effect of trauma-related rumination on trauma intrusions and associated distress. In addition, based on current theories and past research findings, trait rumination and existing depression were proposed to moderate the effect of induced trauma-related rumination on trauma intrusions. Study 3 results indicated that higher levels of trait rumination were associated with greater effects of trauma-related rumination on occurrences of trauma intrusions. Study 4 modified the methodology of Study 3 and found preliminary evidence that trauma-related rumination maintains intrusion-related distress, but not occurrences of intrusions. These findings provide preliminary evidence for the causal role of trauma-related rumination and the moderating role of trait rumination; however the findings were somewhat inconsistent between the two studies and several null results were observed (including the failure of current depression to moderate outcomes). Based on these findings, Study 5 examined whether a brief mindfulness induction after trauma film exposure would reduce trauma-related rumination, and whether the reduction in trauma-related rumination would consequently decrease trauma intrusions and associated distress. The brief induction of mindfulness failed to increase state mindfulness or to reduce rumination and intrusions and associated distress relative to a relaxation control. An examination on the effects of trait mindfulness indicated that it selectively influences trauma-related rumination but not intrusive experiences. The theoretical and clinical implications of Studies 1-5 are discussed.
Keywords: Posttraumatic stress disorder, Trauma, Trauma film, Analogue Trauma, Intrusion, Intrusive memory, Rumination, Comorbid depression, Mindfulness
Subject: Psychology thesis
Thesis type: Doctor of Philosophy
School: School of Psychology
Supervisor: Reg Nixon