Intrusive memory quality in posttraumatic stress disorder and depression : a multimethod comparison using self-report, narrative measures and psychophysiological responding
Creators: name: Parry, Lian Vanessa
Publisher: name: The Australian National University
Year: 2012
Subjects: subject: RC552.P67 P37 2012
subject: Post-traumatic stress disorder
subject: Intrusive thoughts
subject: Depression, Mental

description: Considerable empirical work has investigated theoretically-driven predictions about the distinctive nature of intrusive memory (IM) phenomena in PTSD. Recently, there has been increasing recognition that intrusive remembering may also play an important role in depression. The accompanying findings have been interpreted as indicating that IMs in depression and PTSD exhibit a large degree of overlap. However, much of the IM research in depression to date has been limited by a range of methodological issues (Brewin, Gregory, Lipton, &amp; Burgess, 2010; Newby &amp; Moulds, 2011). This dissertation attempted to address such limitations by applying a multimethod approach to the comparison of IM phenomenology across depressed, PTSD and non-clinical groups. Study 1 compared IM phenomenology using self-report and narrative data while Study 2 combined a script-driven imagery task and self-report measures to consider the role of psychophysiological arousal during trigger event recall. Results confirmed that IMs in depression and PTSD share some degree of overlap but differ on other key features. Specifically, IMs in PTSD were found to be more sensory-perceptual in nature, accompanied by more physical sensations and rated as more distressing than the IMs in depression. The IMs in PTSD were also characterised by a lack of temporal context compared to ordinary memory segments, a difference which was not observed for the depressed group. Furthermore, compared to depressed and control participants, the PTSD group exhibited significantly greater physiological arousal, particularly heart rate responses, whilst recalling trigger events. Although group differences were not found for self-reports of IM-related "nowness", ratings of nowness and physical sensations were strongly positively correlated with PTSD symptom severity. In contrast, no such relationship was found between nowness, physical sensations and severity of dysphoria in the depressed group. Taken together, the results of Studies 1 and 2 present several theoretical and clinical implications. Firstly, the findings support the view that the processing and encoding disruptions thought to underlie IMs in PTSD differ in distinctive and conceptually important ways from those that occur with depression. Specifically, the characteristic sensory-perceptual quality of IMs in PTSD is consistent with a dominance for data-driven or sensory-perceptual processing over conceptual processing during PTSD trigger events, which does not appear to be the case for depression. This corresponds with models of PTSD (Brewin, Dalgleish, &amp; Joseph, 1996; Brewin et al., 2010; Ehlers &amp; Clark, 2000) which suggest that IMs in PTSD are due to information processing disruptions triggered by extreme levels of fear and arousal at the time of the event. This results in poorly contextualised, sensory-based representations which may be less available to conscious recall, yet prone to automatic triggering and accompanied by a re-experiencing of the emotions and physiological arousal from the original event. The heightened physiological responding in the PTSD compared to the depressed group also suggests important discrepancies in the remembering experiences of trigger events in PTSD and depression, and may encourage more avoidant coping mechanisms in PTSD. In contrast, the depressed and non-clinical control groups differed little on self{u00AD}report and narrative-based IM phenomenology or in terms of physiological responsivity during the script-driven imagery task. However, depressed group memories contained a greater proportion of self-relevant devaluative content than those of the other two groups, underscoring the role of schema-level processes in this disorder. Such findings complement previous studies which have distinguished between IMs as a common feature of several psychological disorders, and "flashbacks", which may be a form of intrusive re-experiencing unique to PTSD (Bryant, O'Donnell, Creamer, McFarlane, &amp; Silove, 2011) with possible PTSD-specific implications for treatment. In light of these findings and the lack of theoretical models which account for the development of IMs in depression, caution is warranted over the direct application of traditionally trauma-focussed interventions to the treatment of depression. Indeed, further research is required both to clarify the mechanisms which give rise to and maintain IMs in PTSD and depression, and to elucidate the treatment rationale and potential contraindications for IM-focussed therapies for depression. In this regard, and as evidenced here, multimethod approaches provide a promising, yet so far neglected, avenue through which ongoing theoretical and clinical controversies in IM research may be addressed.