Melbourne School of Psychological Sciences - Theses
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ItemTrauma and psychosis: investigating the role of post-traumatic intrusions, schemas and avoidance( 2016)Increasing evidence suggests that childhood trauma may play a role in the aetiology of psychosis, leading to suggestions that trauma-related symptoms may be mechanisms in the process. Two prominent cognitive models implicate post-traumatic intrusions and trauma-related schemas and emotion as key mechanisms. Neither of the models has been extensively tested, and both have implications for the content of hallucinations and delusions in relation to traumatic experiences. The aims of the current study are to 1) investigate statistical associations between the severity of trauma and psychosis, 2) investigate phenomenological associations between trauma, post-traumatic intrusions, hallucinations and delusions, and 3) explore the relationship between trauma-related avoidance and psychosis. Sixty-six people with first episode psychosis aged between 15 and 24 years were assessed for childhood trauma, post-traumatic stress disorder (PTSD) symptoms, psychotic symptoms and experiential avoidance. The content of hallucinations, delusions, post-traumatic intrusions and traumatic experiences (up to five of each) was assessed. Content relationships between hallucinations, trauma and post-traumatic intrusions were categorised as ‘direct’ (where hallucination content was identical to trauma or intrusion content), ‘indirect’ (where hallucinations contained elements of trauma/intrusion-specific content but were not exact representations of traumas/intrusions) or ‘thematic’ (where hallucinations were related to trauma or intrusions at the level of broader, schema-related themes). Sixty-five percent of the sample had experienced childhood trauma, and 26% met diagnostic criteria for PTSD. Childhood trauma severity was correlated with hallucination and delusion severity with moderate effect sizes (although the correlation with hallucinations did not reach significance). Post-traumatic intrusions correlated with both hallucinations and delusions with moderate to large effect sizes. In terms of hallucination content, 78% of people with hallucinations and childhood trauma had hallucinations related in content to their trauma. These relationships were primarily thematic, although a notable minority (25%) had hallucination content directly representative of their trauma. Sixty-four percent of people had more than one type of relationship (direct, indirect, thematic, or no relationship) between their trauma and hallucination content. Of those with hallucinations and post-traumatic intrusions, 73% experienced hallucinations related in content to their post-traumatic intrusions. For delusion content, 89% of people with delusions and trauma had delusional content related to their trauma. Relationships between childhood trauma, avoidance, hallucinations and delusions were investigated, and it was found that childhood trauma was correlated with experiential avoidance (with a moderate effect size), and that both experiential avoidance and post-traumatic avoidance were correlated with hallucinations and delusions (with moderate effect sizes). In a series of multiple linear regressions, post-traumatic intrusions (but not childhood trauma, post-traumatic avoidance, experiential avoidance or maladaptive schemas) were independently associated with hallucination severity and explained 13% of the variance in hallucinations. Post-traumatic intrusions and maladaptive schemas (but not childhood trauma, post-traumatic avoidance or experiential avoidance) were independently associated with delusion severity, and explained 14% and 5-8% of the variance in delusion severity respectively. These findings suggest that post-traumatic intrusions and maladaptive schemas may be particularly important mechanisms in the relationship between trauma and psychosis, and may be playing a stronger role than avoidance. This has implications for the treatment of trauma and PTSD symptoms in people with psychosis. Research trialling interventions that specifically target post-traumatic intrusions and schemas in people with early psychosis who have experienced childhood trauma is recommended.
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ItemCognitive processing associated with hallucinations for At Risk Mental State( 2013)To date there has been limited investigation of cognitive factors associated with the experience of hallucinations for individuals identified as being at Ultra-High Risk (UHR) for psychosis. This study is the first to comprehensively examine the relationship between auditory hallucinations within a UHR population and prominent cognitive models of perceptual disturbances. Source monitoring, appraisal of cognitive intrusions and metacognition were compared between three groups: a UHR group reporting auditory hallucinations, a UHR comparison group without hallucinations and a non-patient comparison group. The UHR group reporting auditory hallucinations displayed distinct deficits in source monitoring and appraisal of cognitive intrusions, indicating that biases in cognitive processing appear to be associated with the development of hallucinations for UHR populations. Additionally, follow up of the UHR participants was conducted in order to examine the association between cognitive processing biases and persistence of hallucinations. Source monitoring deficits as well as beliefs about the omnipotence of voices were strongly associated with the persistence of hallucinations over the follow up period. This is the first study to demonstrate that distinct cognitive biases are associated with the development of hallucinations during the UHR period. These results provide evidence that cognitive biases may contribute to the emergence of hallucinations, prior to the onset of frank psychosis.