Association Between Childhood And Adulthood Adversity and Schizotypy

544 Pages·2014·13.72 MB·English

by  Tjasa Velikonja

The relationship between childhood
trauma and schizotypy and the pathways
underlying this association

Tjasa Velikonja

Submitted for the award of PhD in
Mental Health Sciences

University College London

June 2014
‘I, Tjasa Velikonja confirm that the work presented in this thesis is my own. Where
information has been derived from other sources, I confirm that this has been
indicated in the thesis.'
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Abstract
There is a growing body of literature demonstrating an association between childhood
trauma and schizotypy (e.g. Afifi et al. 2011;Myin-Germeys et al. 2011). However,
more research is required to build on methodological limitations of previous studies,
explore the possible differential effects of specific trauma types and expand the focus
from a single contributor (e.g. psychological, biological) by considering the
additive/interactive contributors to schizotypal symptomatology. The aim of the thesis
was to explore the relationship between a range of childhood traumatic experiences
and schizotypy whilst also incorporating several social, psychological and genetic
factors underlying these relationships. Participants were recruited as a part of a
cross-sectional case-control study conducted in the London Boroughs of Lambeth
and Southwark. The thesis covers a subsample of controls (N=212), healthy
volunteers, aged 18-64 and residents in the same geographical area. Data were
gathered using an in-depth standardised interview regarding childhood abuse
(Childhood Experience of Care and Abuse - CECA) and The Structured Interview for
Schizotypy – Revised (SIS-R) measuring a range of schizotypal symptoms and signs.
The study found a linear association of total trauma and schizotypy (adj. β=.88,
p=0.004), with the strongest associations observed for psychological (adj. OR=4.85,
p=0.039) and physical abuse (adj. OR=3.56, p=0.003). These particular types of
trauma had an especially robust effect on positive schizotypal traits (psychological:
adj. OR=3.79, p=0.013; physical abuse: adj. OR=2.32, p=0.042), which are
attenuated forms of positive symptoms of schizophrenia (e.g. hallucinations,
delusions). Negative beliefs about self/others and depression were the main
mediators of these associations. A strong relationship was found for genetic risk of
psychosis and increased schizotypy (adj. β=3.41, p=0.015). Other moderators of the
childhood trauma - schizotypy association were intrusive life events (adj. β=4.20,
p=0.045). This study provides further insights into the association between childhood
trauma and schizotypy and gives clues to pathways underlying this association.
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List of Contents

INTRODUCTION 15
CHAPTER 1 - LITERATURE REVIEW: SCHIZOTYPY 15
1.1 What are schizotypy and schizotypal personality disorder? 17
1.1.1 Definitions of the concepts 18
1.1.2 The multifactorial nature of schizotypy 27
1.1.3 The heterogeneity of schizotypy measures 29
1.1.4 Socio-demographic characteristics and schizotypy 44
1.1.5 Schizotypy and the development of psychosis / The continuum model 46
1.2 Heritability of schizotypy 53
CHAPTER 2 - LITERATURE REVIEW: CHILDHOOD TRAUMA AND SCHIZOTYPY 63
2.1 Childhood trauma and schizotypy association 65
2.1.1 Introduction to the childhood trauma and schizotypy association 67
2.1.2 Empirical literature search strategy 71
2.1.3 Results 73
2.1.4 Discussion 83
2.1.5 Methodological issues 89
2.2 Childhood trauma in relation to psychotic-like symptoms 100
2.2.1 Introduction and search strategy 101
2.2.2 Results 104
2.2.3 Discussion 115
2.3 Possible pathways underlying the childhood trauma – schizotypy association 123
2.3.1 Hypothesised theoretical models 126
2.3.2 The effects of adult traumatic experiences /Life events 133
2.3.3 The role of dissociation and PTSD 139
2.3.4 The effect of cannabis use 145
CHAPTER 3 - METHODOLOGY 155
3.1 Aims and Hypotheses 157
3.1.1 Aims of the thesis 158
3.1.2 Hypotheses 158
3.2 Study design 160
3.2.1 Experimental design 161
3.2.2 Sample size calculation 163
3.3 Sample/Data collection 165
3.4 Main assessment tools 173
3.4.1 Structured Interview for Schizotypy Revised (SIS-R) 176
3.4.2 Community Assessment of Psychic Experiences (CAPE) 190
3.4.3 Childhood Experience of Care and Abuse (CECA) 192
3.4.4 Bullying Questionnaire 203
3.4.5 Life Events and Difficulties Schedule (LEDS) 203
3.4.6 Brief Core Schema Scales (BCSS) 205
3.4.7 Hamilton Rating Scale for Depression (HRSD) 206
3.4.8 Family Interview for Genetic Studies (FIGS) 207
3.4.9 Cannabis Experience Questionnaire (CEQ) 208
CHAPTER 4 - RECRUITED SAMPLE AND DATA MANAGEMENT 210
4.1 Recruited sample 212
4.1.1 Socio-demographic characteristics of the final sample 215
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4.2 Data analyses 218
4.2.1 Childhood trauma and schizotypy association 219
4.2.2 Childhood trauma and life events interaction and schizotypy 226
4.2.3 Childhood trauma and familial risk interaction and schizotypy 229
4.2.4 Childhood trauma and schizotypy and the effects of cannabis 231
4.2.5 Possible underlying mechanisms supporting childhood trauma – schizotypy association/
mediation effects 233
CHAPTER 5 - RESULTS 237
5.1 Is there support for the childhood trauma and schizotypy association? 247
5.2 Life events (and interaction with childhood trauma) and schizotypy association 263
5.3 Familial risk for psychosis (and interaction with childhood trauma) and schizotypy
association 267
5.4 Cannabis use (and interaction with childhood trauma) and schizotypy association
272
5.5 Mediation effects / Pathways from childhood trauma to schizotypy 277
CHAPTER 6 - DISCUSSION 291
6.1 Overview of the main findings 293
6.2 Study findings and link to existing literature 300
6.3 Study limitations 325
CHAPTER 7 - FINAL REMARKS 341
7.1 Brief summary of the findings (Integrated model) 343
7.2 Clinical Implications 346
7.3 Future directions 354
REFERENCES 358
APPENDICES 443
Appendix I Scoring guide for the quality assessment of the empirical research papers 445
Appendix II Table Suppl.1: continued summary of studies on childhood adversity in relation to
psychosis-like experiences 447
Appendix III Participant Information Sheet and Consent Form 451
Appendix IV Psychosis Screening Questionnaire 456
Appendix V MRS Sociodemographic Schedule 457
Appendix VI Wechsler Adult Intelligence Scale (3rd ed.) (WAIS-III, abbreviated) 465
Appendix VII Structured Interview for Schizotypy-Revised (SIS-R) 468
Appendix VIII Community Assessment of Psychic Experiences (CAPE) 487
Appendix IX Childhood Experience of Care and Abuse (CECA) ‘Interview Version’ and Bullying
Questionnaire 490
Appendix X Life Events and Difficulties Schedule (LEDS) 497
Appendix XI Brief Core Schema Scales (BCSS) 501
Appendix XII Hamilton Rating Scale for Depression (HRSD) 502
Appendix XIII Family Interview for Genetic Studies (FIGS) 508
Appendix XIV The Cannabis Experiences Questionnaire (CEQ) 516
Appendix XV Table Suppl.2: Socio-demographics of Southwark and Lambeth Boroughs 523
Appendix XVI Additional Result Tables 524

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List of Tables

Table 1: Measures of general schizotypy 35
Table 2: Measures of attenuated psychotic symptoms 40
Table 3: Summary of studies on childhood trauma and schizotypal traits 74
Table 4: Summary of studies on childhood trauma in relation to psychosis-like experiences (PSE) 105
Table 5: Ethnic distribution for England and London Boroughs of Lambeth and Southwark 163
Table 6: Gender and ethnicity of the recruited sample according to the three different sources of
recruitment 168
Table 7: Ethnic groups (and gender) of the total sample (comparison with ethnic distribution in
Lambeth and Southwark Boroughs) 213
Table 8: Gender and ethnic distribution of the thesis sample 214
Table 9: Ethnicity comparison of those with completed SIS-R (‘included’) and those without SIS-R
(‘excluded’) 215
Table 10: Source of recruitment comparison of those with completed SIS-R (‘included’) and those and
those without SIS-R (‘excluded’) 215
Table 11: Complete socio-demographic characteristics of the thesis sample 217
Table 12: Frequencies and gender comparison in reported total trauma and all distinct trauma types 239
Table 13: Frequencies and gender comparison of psychological and sexual trauma (including all levels
of severity) 240
Table 14: Frequencies for multi-victimisation and between gender comparison 240
Table 15: Frequencies and comparison between ethnic groups in reported total trauma and all distinct
trauma types 240
Table 16: Mean schizotypy scores (SIS-R) and attenuated psychotic symptoms scores (CAPE) -
between gender comparison 244
Table 17: Frequencies of schizotypal traits in a total sample and between gender comparisons 245
Table 18: Comparison between ethnic groups on mean schizotypy (SIS-R) and attenuated psychotic
symptoms (CAPE) scores 246
Table 19: Associations between total trauma (and all distinct trauma types) and total schizotypy 248
Table 20: Association between separation from a parent and parental death experiences and total
schizotypy 249
Table 21: Association between trauma types and top 20% and top 10% of schizotypy scorers 251
Table 22: Association between trauma types and top 20% and top 10% of scorers on positive
schizotypy 252
Table 23: Association between trauma types and top 20% and top 10% of scorers on
negative/disorganised schizotypy 253
Table 24: Association between number of types of traumatic experiences and total, positive and
negative/disorganised schizotypy 255
Table 25: Association between trauma types (different levels of frequency and severity) and total
schizotypy 255
Table 26: Association between age of trauma occurrence and total, positive and negative/disorganised
schizotypy dimensions 257
Table 27: Gender comparison of association between trauma types and total schizotypy 258
Table 28: Associations between total trauma (and all distinct trauma types) and attenuated/psychotic-
like symptoms total (on CAPE measure) 261
Table 29: Associations between total trauma (and all distinct trauma types) and CAPE positive and
CAPE negative dimensions 262
Table 30: Frequency of recent life events and between gender comparison 264
Table 31: Frequency of recent life events among individuals with and without childhood trauma 264
Table 32: The interaction effects of the recent life events and difficulties and childhood trauma on total
schizotypy score 265
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Table 33: The interaction effects of recent life events and difficulties and childhood trauma on positive
and negative/disorganised schizotypy 266
Table 34: Frequency of familial risk of psychosis (‘psychosis/narrow’ and ‘any mental illness/broad’
definition) 268
Table 35: The interaction effects of familial risk for psychosis and childhood trauma on total schizotypy 270
Table 36: The interaction effects of familial risk for psychosis and childhood trauma on positive and
negative/disorganised schizotypy 270
Table 37: The interaction effects of familial risk for psychosis (including any mental illness of a first
degree family member) and childhood trauma types on total schizotypy score 271
Table 38: Frequency of lifetime cannabis use 273
Table 39: Frequency of current cannabis use and lifetime dependency 273
Table 40: Frequency of lifetime cannabis use among those with/without childhood trauma 274
Table 41: Types of cannabis among those with/without childhood trauma 274
Table 42: The interaction effects of cannabis use and childhood trauma on schizotypy 275
Table 43: The interaction effects of the age of cannabis use and childhood trauma on schizotypy 275
Table 44: The association between the frequency of cannabis use and total and positive and
negative/disorganised schizotypy 276
Table 45: The comparison between the associations of type of cannabis used and schizotypy 276
Table 46: The frequency of lifetime dissociation symptoms among those with/without childhood trauma 278
Table 47: The frequency of recent dissociation symptoms among those with/without childhood trauma 278
Table 48: The association between recent dissociation/derealisation symptoms and total, positive and
negative schizotypy 278
Table 49: Mean scores on negative beliefs about self/others and the depression scale 279
Table 50: Mean scores on negative beliefs about self/others and the depression scale among those
with/without childhood trauma 279
Table 51: The effects of the negative beliefs/ depression scores and childhood trauma on schizotypy
scores 280
Table 52: The effects of the negative beliefs/ depression scores and childhood trauma on positive and
negative/disorganised schizotypy 280
Table 53: Associations between different types of childhood trauma and schizotypy total scores, split
into total, direct and indirect effects/pathways via possible mediators 282
Table 54: Main study findings according to each of the hypotheses 296
Table 55: The prevalence of trauma in the present study compared to UK study (NSPCC) 302

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List of Figures

Figure 1: Summary of phases preceding schizophrenia 27
Figure 2: Flowchart of studies included in the literature review - 1 72
Figure 3: Flowchart of studies included in the literature review - 2 104
Figure 4: Diagrammatic presentation of factors predicting psychosis-proneness 125
Figure 5: Hypothesised sociodevelopmental and neurodevelopmental pathways to psychosis 132
Figure 6: The total sample size needed for increase/decrease in odds ratio (at constant power) – for
logistic regression analysis 164
Figure 7: The total sample size needed for different statistical power (if OR=2) – for logistic regression
analysis 164
Figure 8: The total sample size needed for different effect sizes – for linear regression analysis 164
Figure 9: Flowchart presentation of the recruitment process 169
Figure 10: Overview of the measures used for analysis for Hypothesis 1, including the variables
extracted from the measures and types of analyses used 219
Figure 11: Overview of the measures used for analysis for Hypothesis 2, including the variables
extracted from the measures and type of analysis used 227
Figure 12: Overview of the measures used for analysis for Hypothesis 4, including the variables
extracted from the measures and type of analysis used 229
Figure 13: Overview of the measures used for analysis for Hypothesis 5, including the variables
extracted from the measures and type of analysis used 231
Figure 14: Overview of the measures used for exploratory mediation analyses (Hypotheses 3 & 5),
including the variables extracted from the measures and type of analysis used 233
Figure 15: Path decomposition into direct and indirect effects 235
Figure 16: Frequencies of schizotypy total scores (SIS-R) - normal distribution of SIS-R total scores 242
Figure 17: Mediation (in percentage) of the effect of household discord on schizotypy 288
Figure 18: Mediation (in percentage) of the effect of psychological abuse on schizotypy 288
Figure 19: Mediation (in percentage) of the effect of physical abuse on schizotypy 288
Figure 20: Mediation (in percentage) of the effect of sexual abuse on schizotypy 289
Figure 21: Mediation (in percentage) of the effect of bullying on schizotypy 289
Figure 22: Conceptual path diagram showing significant associations between childhood trauma and
schizotypy, direct and indirect paths 290
Figure 23: Integrated model - hypothesised diagram showing pathways between childhood trauma
and schizotypy according to the present findings; direct and indirect paths 345

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Acknowledgments

I would like to express my deepest appreciation to all my supervisors, Prof. Sonia
Johnson, Dr. Oliver Mason and Dr. Helen L. Fisher for their continuous guidance,
encouragement and unwavering patience over the past three years. Your immense
knowledge and advice on both research and my career have really been invaluable.
Special thanks go to Dr. Craig Morgan from the Institute of Psychiatry for giving me
the opportunity to be a part of such an exciting study and I greatly appreciate all the
hard work of staff working on the EU-GEI project. I feel very humbled that I worked
with such an inspiring research team. In particular, I would like to acknowledge
Kathryn Hubbard whose enthusiasm and relentless support made the participants’
recruitment really pleasurable. I will also always be indebted to all individuals who
participated in the study and were instrumental for its successful completion.
Finally, I would like to thank my beloved boyfriend for his endless understanding and
emotional backing and all my family and friends for believing in me. Without you I
truly would not have been able to complete this challenging but fulfilling journey.
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Introduction

As psychotic disorders, such as schizophrenia, place a major burden on the
individual, family and society, it is important to find ways to identify as early as
possible who is at risk for such disorders. One way to do this would be to develop a
better understanding of the aetiology of subclinical manifestations of psychosis such
as schizotypy. Therefore, the importance of schizotypy research lies in the potential
to identify the fundamental features of liability to psychosis and could have
substantial implications for prevention, clinical assessment and treatment
formulation.
Literature suggests that the psychosis phenotype is expressed at subclinical
levels (e.g. van Os et al. 2009). The term ‘psychosis continuum’ denotes the gradual
transition from subclinical attenuated psychotic experiences or schizotypal traits to
clinically relevant psychotic disorders as opposed to a sharp categorical division
between disorder ‘absent’ or ‘present’. This proposition is based on the pioneering
work of Rado (1960) followed by Meehl’s (1962) conceptualisation of schizotypy.
According to their views, schizotypy represents a fundamental liability to
schizophrenia and underlies a range of clinical manifestations ranging between
healthy variation and severe mental illness.
The multidimensionality of the schizotypy construct resembles schizophrenia
symptomatology (e.g. Lenzenweger et al. 1991) and can be clustered as three
dimensions: a positive cluster (e.g. unusual perceptions, magical thinking, ideas of
reference), a negative cluster (e.g. restricted affect, social isolation) and a
disorganized cluster (e.g. odd behaviour, odd speech) (Claridge et al. 1996;Vollema
and Vandenbosch 1995). Similarly, the ‘schizophrenia prodrome’ (period preceding
the diagnosis of schizophrenia) also reflects attenuated schizophrenia symptoms,
making these constructs not easily distinguishable (Bedwell and Donnelly 2005).
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