Writing a structured abstract for the thesis

Abstract

BackgroundStudies investigating recognition memory (RM) in schizophrenia report a selective deficit in autonoetic awareness and intact levels of noetic awareness for visual stimuli. It has been suggested that abnormalities in autonoetic awareness result from a breakdown in frontal strategic memory processes involved in encoding and retrieval and executive functions linked to reality monitoring and decision making.AimsThe aims of this thesis were to investigate four predictions arising from these proposals: (1) If decrements in autonoetic awareness arise from a ‘central’ impairment, then these abnormalities should not be domain-specific; (2) if autonoetic awareness abnormalities arise from a breakdown in executive processes, then these abnormalities should correlate with executive dysfunction; (3) because autonoetic awareness is a necessary correlate of episodic memory, then patients with schizophrenia should also be impaired in contextual memory; and (4) autonoetic awareness abnormalities are likely to be more severe in schizophrenia, a condition associated with marked executive dysfunction relative to major depressive disorder, in which executive dysfunction is less marked.MethodThe remember/know paradigm was used to investigate RM across four modalities (verbal, visual, auditory and olfactory) in three groups: patients with schizophrenia (N=19), patients with major depressive disorder (N=21), and normal controls (N=24). A subgroup of the same schizophrenia patients (N=14) were also tested for temporalorder memory for words, line drawings and abstract drawings. Autobiographical memory was assessed in patients using the Autobiographical Memory Interview. Executive function and working memory were assessed using the Wisconsin Card Sorting Test and the Letter-Number Sequencing Test, respectively.ResultsAutonoetic awareness abnormalities were evident in patients with schizophrenia for voices (p<0.05) and smells (p<0.05). These deficits were restricted to schizophrenia, with patients with major depressive disorder performing intermediate to both schizophrenia patients and normal controls. A subgroup of the same schizophrenia patients also exhibited impaired temporal-order memory (p<0.05), but this impairment was restricted to words and also evident in patients with major depressive disorder (p<0.05). Executive dysfunction and reduced working memory was restricted to patients with schizophrenia, but none of these measures correlated with decrements in autonoetic awareness or temporal-order memory. Autobiographical memory for both patient groups was within the normal range.Conclusions: Impaired autonoetic awareness for voices and smells in the same cohort of schizophrenia patients provide some support for proposals that abnormalities in autonoetic awareness stem from a breakdown in ‘central’ rather than domain-specific processes. Furthermore, these patients were also impaired for temporal-order memory, which suggests that strategic memory processes were also implicated in these schizophrenia patients.