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Durham E-Theses Delusions and attentional bias Leafhead, Katherine M. How to cite: Leafhead, Katherine M. (1997) Delusions and attentional bias, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/5007/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk Delusions and Attentional Bias Katharine M. Leafhead PhD Thesis University of Durham Department of Psychology 1997 The copyright of this thesis rests with the author. No quotation from it should be published without the written consent of the author and information derived from it should be acknowledged. -3 JUL 1S37 Abstract A research method for investigating delusional beliefs is outlined by adopting the delusional belief that one is dead (the Cotard delusion) as a model delusion. Detailed analyses of published case reports of the Cotard delusion demonstrate that the term 'syndrome' as it is currently applied to the belief that one is dead is not helpful in terms of our understanding of the delusion. Four new case studies of the Cotard delusion suggest that preoccupation with belief may play a role in the formation and maintenance of delusions. Preoccupation with delusional belief was investigated using a variant of the 'emotional' Stroop paradigm, commonly used in investigating anxiety disorders. Three individuals with the Cotard delusion, and diagnosed as suffering from depression, showed attentional biases toward words related to the theme of death. Two of the individuals had no history of anxiety and showed no bias toward words related to generalised anxiety. It was therefore suggested that the locus of attentional biases in delusions may be preoccupation with delusional belief, rather than anxiety per se. Consistent with this, a patient with fixed grandiose delusional beliefs, diagnosed with schizophrenia, and not suffering from anxiety, showed attentional bias toward words related to his delusional beliefs. Attentional bias failed to be demonstrated in a group of people with delusions arising in the context of schizophrenia, and reasons for this are discussed. Finally, three groups of individuals, who were free form any form of psychopathology, each showed a trend towards longer colour-naming times towards words related to their respective interests, but none of these were significant. It is concluded that attentional biases in delusions serve to reinforce delusional beliefs by constantly focusing the individual's attention onto delusion- relevant material. Implications for further research are discussed. ii Table of Contents Chapter One: Research into delusions 1 Definitions and contexts What is a delusion? 1 Who suffers from delusions? 7 Issues in research Explanations for delusions 7 Symptoms and syndromes 10 Adopting a model delusional belief 13 The Cotard delusion Introduction 14 An approach to research and an explanation 14 The Cotard delusion, and depersonalisation and derealisation 19 The Cotard delusion and the philosophy of existence 21 Chapter Two: The Cotard delusion 24 Introduction 24 The Cotard syndrome debate 24 Cotard's case reports Introduction 28 Analysis of Cotard's case reports 29 Discussion ofCotard's case reports 33 Case reports published in English Introduction 34 Analysis of case reports published in English 36 Discussion of case reports 40 Discussion 43 Chapter Three: Single cases of the Cotard delusion 50 Introduction 50 Four case studies of the Cotard delusion RB: A case of anxious agitation 52 Case description 52 Delusional beliefs 52 JA: A bodily delusion as an explanation of a painful life event 54 Case description 54 iii Delusional beliefs 54 MB: A chronic case of the Cotard delusion 56 Case description 56 Delusional beliefs 57 JK: A severe case of the Cotard delusion 58 Case description 58 Delusional beliefs 60 Formal testing Introduction 67 Warrington Recognition Memory Test 70 Hospital Anxiety and Depression Scale 71 Magical Ideation Scale 72 Discussion of formal testing 74 Analysis of case studies 75 Discussion 77 Chapter Four: Attentional bias in the Cotard delusion 85 Introduction 85 Attentional bias in psychopathological disorders Introduction 86 The Stroop colour-naming paradigm 86 Attentional bias in psychopathological disorders using the 'emotional' Stroop colour-naming paradigm 92 Attentional bias in anxiety and depression 94 Attentional bias in delusions 100 Attentional bias in a single case of the Cotard delusion Introduction 102 Investigation 102 Method 100 Results 102 Discussion 105 Replication of attentional bias in the Cotard delusion Introduction 107 Investigation 107 Method 107 Results 108 Discussion 110 Discussion 112 iv Chapter Five: Attentional bias in a grandiose delusion 114 Introduction 114 Investigation Case description 115 Method 116 Results 118 Discussion 120 Chapter Six: Attentional bias in schizophrenic delusions 123 Introduction 123 Investigation Method 123 Results Errors 126 Colour-naming times 126 Hospital Anxiety and Depression (HAD) scores 129 Correlational analyses of HAD scores and colour-naming interference indices 130 Discussion 130 Chapter Seven: Attentional bias in normals 134 Introduction 134 Attentional bias in undergraduate students Introduction 135 Method 135 Results Errors 138 Colour-naming times 140 Hospital Anxiety and Depression (HAD) scores 142 Correlational analyses of HAD scores and colour-naming interference indices 143 Discussion 143 Attentional bias in motor-cycle enthusiasts Introduction 145 Method 145 Results Errors 146 Colour—naming times 148 Hospital Anxiety and Depression (HAD) scores 149 Correlational analyses of HAD scores and colour-naming interference indices 149 Discussion 150 Attentional bias in rowers Introduction 151 Method 152 Results Errors 153 Colour-naming times 155 Hospital Anxiety and Depression (HAD) scores 156 Correlational analyses 157 Discussion 157 Discussion 158 Chapter Eight: General discussion 160 References 172 Appendices 183 vi Tables Chapter Two Table 2.1: List of symptoms noted by Cotard (1882) and their occurrence in his pure cases. 30 Table 2.2: Symptoms noted for Cotard's (1882) pure cases according to symptom group. 33 Table 2.3: Occurrence of Cotard symptoms in case reports published in English. 37 Table 2.4: Symptoms noted for case reports published in English according to symptom group. 39 Chapter Three Table 3.1: Status of delusional beliefs at the time of testing. 69 Table 3.2: Scores for RB, J A, MB & JK on the Warrington Recognition Memory Test for words and faces. 70 Table 3.3: Scores for RB, JA, MB & JK on the Hospital Anxiety and Depression (HAD) Scale. 71 Table 3,4 Scores for RB, JA, MB & JK on the Magical Ideation Scale. 72 Table 3.5 Symptoms noted in the four single cases of the Cotard delusion. 76 Table 3,6 Symptoms noted for the four cases according to symptom group. 77 Chapter Four Table 4.1: Number of errors made by controls and by JK in colour-naming word lists. 107 Table 4.2: Mean times (in seconds) taken by controls and the times taken by JK to colour-name word lists. 107 Table 4.3: Number of errors made by controls and by patients JA and MB in colour-naming word lists. 113 Table 4.4: Times (in seconds) taken by JA and MB to colour-name word lists. 113 Chapter Five Table 5.1: Mean times (seconds) taken by SD to colour-name word lists. 123 Chapter Six Table 6.1: Presence of thought disorder and/or hallucinations. 128 Table 6.2a: Colour-naming errors made by the schizophrenia group. 131 vii Table 6.2b: Task-switching errors made by the schizophrenia group. 131 Table 6.3: Means and standard deviations for colour-naming times in test and neutral word lists. 132 Table 6.4: HAD scores for the schizophrenia group. 133 Chapter Seven Table 7.1a: Colour-naming errors made by students in the Lent term. 142 Table 7.1b: Colour-naming errors made by students in the Summer term. 142 Table 7.2: Mean colour-naming errors made by students in the Lent and Summer terms. 142 Table 7.3: Mean colour-naming times (sees) of students in the Lent and Summer terms. 144 Table 7.4: Student HAD scores. 145 Table 7.5a: Colour-naming errors made by bikers. 150 Table 7.5b: Colour-naming errors made by controls. 150 Table 7.6: Mean colour-naming errors by bikers and controls. 151 Table 7.7: Mean colour-naming times (sees) of bikers and controls. 152 Table 7.8: HAD scores for bikers and controls. 153 Table 7.9a: Colour-naming errors made by rowers. 156 Table 7.9b: Colour-naming errors made by controls. 156 Table 7.10: Mean colour-naming errors made by rowers and controls. 156 Table 7.11: Mean colour-naming times (sees) of rowers and controls. 158 Table 7.12: HAD scores for rowers and controls. 159 viii Illustrations Chapter Four Figure 4.1: z-score differences between JK's times to colour-name words in the test and neutral lists. 109 Figure 4.2: z-score differences between JA's times to colour-name words in the test and neutral lists. 115 Figure 4.3: z-score differences between MB's times to colour-name words in the test and neutral lists. 115 Chapter Five Figure 5.1: z-score differences between SD's times to colour-name words in the test and neutral lists.