Author: Caitlin Hitchcock
Hitchcock, Caitlin, 2014 Overgeneral Memory, Trauma, and Psychopathology in Children, Flinders University, School of Psychology
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Overgeneral memory (OGM) occurs when an individual demonstrates impaired retrieval of specific, single incident events from autobiographical memory. OGM theorists have argued that childhood trauma will increase OGM as this retrieval style will be adaptive for emotion regulation in the short term following trauma. However, OGM is thought to become associated with psychopathology if maintained over the longer term (Williams, 1996). This proposition has not been directly tested, although OGM is consistently associated with persistent depression in adolescents (see Hitchcock, Nixon, & Weber, 2013, for recent review of childhood OGM). Further, it is unclear how OGM relates to paediatric posttraumatic stress disorder (PTSD). Better understanding of whether the relationship between OGM and psychopathology may change over time will indicate at what point certain clinical interventions may be optimally timed following childhood trauma (especially those that target memory retrieval processes). This thesis comprised the first examination of OGM and the course of psychological symptoms in young people exposed to trauma. This investigation was driven by two research questions. First, how does OGM relate to psychopathology following childhood trauma exposure? In particular, I explored how OGM related to symptoms of PTSD and depression, and whether time since trauma moderated these relationships. Second, does the CaR-FA-X model (Williams et al., 2007) adequately explain childhood OGM? Specifically, key components of the model, namely the capture and rumination, functional avoidance, and executive control mechanisms, were assessed. Study 1 longitudinally examined OGM and the development of psychological symptoms over six months following childhood trauma exposure. The capture and rumination, and executive control mechanisms of the CaR-FA-X model were also assessed. Results indicated that the relationship between OGM and PTSD symptoms changed over time. Interestingly, OGM was negatively related to PTSD symptoms at six months post-trauma. No evidence was found for a relationship between OGM and depression, or for the assessed CaR-FA-X mechanisms to explain OGM. Study 2 built upon these findings by providing preliminary, cross-sectional evidence that the relationship between OGM and PTSD symptoms may continue to change years after trauma exposure. All three mechanisms of the CaR-FA-X model were assessed to thoroughly test the theory. No evidence was found for the CaR-FA-X model as a whole, although some results were consistent with the proposed role of functional avoidance. Based on these results, Study 3 and Study 4 experimentally assessed the key assumptions of functional avoidance. Results indicated that overgeneral retrieval of memories of an adverse event regulated affect. This provided further support for the hypothesised role of the functional avoidance mechanism. Three main conclusions were drawn from results. First, findings indicated that OGM may initially be adaptive for mood regulation, and also PTSD symptoms, following childhood trauma. At this initial stage, functional avoidance appears to explain OGM. Second, OGM may change to become maladaptive if used in the longer term. This change may occur years after exposure, and at this point OGM may become associated with depression. Once maladaptive, the capture and rumination, and executive control mechanisms of the CaR-FA-X model may become operational. Finally, the mechanism underlying OGM's change from adaptive to maladaptive is unclear. Theory and previous research suggest this may occur due to OGM generalising from a trauma memory to retrieval of other autobiographical memories. Further research on the trajectory of OGM following childhood trauma, and the cognitive processes underlying the retrieval style will improve the efficacy of emerging clinical interventions. Ultimately, further understanding of OGM may help to reduce the impact and severity of psychopathology following childhood trauma.
Keywords: overgeneral memory,trauma,PTSD,depression,children
Subject: Psychology thesis
Thesis type: Doctor of Philosophy
Completed: 2014
School: School of Psychology
Supervisor: Reg Nixon