The Comorbidity Between Eating Disorders and Anxiety Disorders

442 Pages·2009·1.85 MB·English

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JESSICA. M. SWINBOURNE
BA (Psych)
GD Science (Psych)

A thesis submitted in fulfillment of the requirements for the degree of
DOCTOR OF CLINICAL PSYCHOLOGY / DOCTOR OF PHILOSOPHY

Department of Psychology
Faculty of Science
The University of Sydney

July 2008
Statement of Originality

This thesis is submitted to the University of Sydney in fulfilment of the requirements for
the Degree of Doctor of Clinical Psychology / Doctor of Philosophy. The work presented
in this thesis is, to the best of my knowledge and belief, original except as acknowledged
in the text. I hereby declare that I have not submitted this material, either in full or in part,
for a degree at this or any other institution.

________________________ ________________________
J.M. Swinbourne Date

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ABSTRACT
Research indicates that eating disorders and anxiety disorders frequently co-occur. The
prevalence of anxiety disorders amongst anorexia nervosa and bulimia nervosa samples
has been reported in a number of investigations. Despite the significant number of
research papers investigating the comorbidity between eating disorders and anxiety
disorders, many are plagued by methodological problems, limiting the usefulness of
findings. Furthermore, there is a significant lack of research examining the prevalence of
eating disorders among anxiety patients, and as a result, the frequency of eating disorder
pathology among patients presenting to specialty anxiety clinics is unclear. The current
research investigated the prevalence of comorbid eating and anxiety disorders amongst
152 women presenting for either eating disorder treatment or anxiety disorder treatment.
The prevalence of anxiety disorders was determined from a sample of 100 women
presenting for inpatient and outpatient eating disorder treatment. The prevalence of eating
disorders was determined from a sample of 52 women presenting for outpatient treatment
of an anxiety disorder. The current study found that 65% of women with eating disorders
also met criteria for at least one comorbid anxiety disorder. Furthermore, 69% reported
the onset of the anxiety disorder to precede the onset of the eating disorder. Of the
anxiety disorders diagnosed, Social Phobia was most frequently diagnosed (42%)
followed by PTSD (26%), GAD (23%), OCD (5%), Panic/Ag (3%) and Specific Phobia
(2%). We also found that 13.5% of women presenting for anxiety treatment also met
criteria for a comorbid eating disorder. The results of this study suggest that the
prevalence of eating and anxiety disorder comorbidity is high. It is hoped that the present
research will have significant etiological and therapeutic implications and further the
understanding of the development and maintenance of eating disorder pathology.

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OVERVIEW

The present research endeavours to investigate the prevalence of comorbid eating
disorders and anxiety disorders. Chapter 1 provides a general overview of the eating
disorders, Anorexia Nervosa, Bulimia Nervosa and Eating Disorder Not Otherwise
Specified, as well as the available literature investigating eating disorders, including
diagnosis, assessment, comorbidity, treatment and outcome. Chapter 2 provides a general
overview of the anxiety disorders including core features and a review of the literature
regarding diagnosis, assessment, comorbidity, and treatment of anxiety disorders.
Chapters 3 and 4 provide a detailed literature review of the research investigating
comorbidity between anxiety and eating disorders. These chapters also pay special
attention to the methodological limitations inherent in much of the research investigating
this area to date. Chapter 5 outlines the aims and objectives for the current study. The
methodology for the current study is described in Chapter 6. Chapter 7 outlines the
characteristics of the samples. Chapter 8 outlines the results obtained from the current
study. Chapter 9 consists of a discussion of the results obtained, as well as a discussion
on the strengths and limitations of the current study and directions for future research in
the area of eating disorder and anxiety disorder comorbidity.

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ACKNOWLEDGEMENTS

I would sincerely like to thank all the women who were so generous with their time and
were willing to participate in my research. Your courage in discussing such difficult and
personal issues was incredible, and without your support this research would not have
been completed. I hope that this research may in some way, help you and others who
continue to struggle with an eating or anxiety disorder.

I would also like to acknowledge the ongoing support from all the health professionals
who were involved in this research. In this regard, I am especially grateful to Adrienne
Alexander, Natalie Crino, Olivia Patrick and Dr Margaret Sheridan.

My sincerest thanks also to my associate supervisors, Dr Caroline Hunt, Dr Maree
Abbott, Professor Janice Russell and Tamsen St Clare, whose assistance throughout this
research was vital. I would also like to thank Dr Margaret Charles for her statistical
assistance throughout this research.

I am indebted to my supervisor, Professor Stephen Touyz, for his constant enthusiasm,
encouragement, support and guidance of this research and thesis. The supervision of such
a respected figure in the area of eating disorders has been instrumental in furthering my
learning in clinical psychology and research. In particular, Stephen has highlighted to me
the importance of continued efforts to improve treatment and outcomes for individuals
suffering from eating disorders.

I would also like to thank my Mum and Dad, my brother Malcolm and sister-in-law Paula
(and my new nephew Alistair) and my Uncle Pete, for their constant love and support
over the years and for never losing faith that I would finally finish my studies. I also
thank my parents for instilling in me a love of learning and for always encouraging me to
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give things a go. I am also lucky to have a wonderful group of friends, who have
provided welcomed distraction, as well as enormous support over many years.

It is with sadness I acknowledge my friend Jared whose life was tragically cut short in
November 2007. I admired Jared’s wisdom, kindness, energy and passion for life. He is
dearly missed by many.

Finally, I would not have completed this research without the incredible love and support
of my husband Banjo. I am constantly amazed by your patience, enthusiasm, your
unwavering belief in me and your endless encouragement. If only I could find the words.

Jessica Swinbourne
July, 2008
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PREFACE

The study presented in this thesis represents research undertaken by the candidate in
conjunction with other professionals and researchers at the Wesley Private Hospital
inpatient and outpatient eating disorder unit, Northside Clinic inpatient eating disorder
unit, Westmead Hospital Anxiety Treatment and Research Unit, Westmead Hospital
Eating Disorder Day Program, the University of Sydney Psychology Clinic and
Psychology and Psychiatry Practices in the Sydney Metropolitan area. Ethics was granted
by the University of Sydney Human Research Ethics Committee, South West Sydney
Area Health Service Human Research Ethics Committee, South West Sydney Area
Health Service Scientific Advisory Committee and Northside Clinic.

The candidate was involved in all aspects of the study and was responsible for
coordinating the study under the supervision of Professor Stephen Touyz, Dr Caroline
Hunt, Dr Maree Abbott, Professor Janice Russell and Tamsen St Clare.

The contributions of the candidate include:
Study design: The candidate was responsible for designing the study, under the guidance
of Professor Stephen Touyz. The candidate was also responsible for recruiting the study
sample of 152 participants from Wesley Private Hospital inpatient eating disorder unit,
Northside Clinic inpatient eating disorder unit, Westmead Hospital Anxiety Treatment
and Research Unit, Westmead Hospital Eating Disorder Day Program, the University of
Sydney Psychology Clinic and Psychology and Psychiatry Private Practices located in the
Sydney Metropolitan area. The candidate was responsible for conducting assessments on
participants, as well as for selecting the assessment measures, questionnaires and
demographic questions utilsed in this study.

Data collection, entry and analysis: The candidate was responsible for all aspects of data
collection, entry and analyses. The candidate was responsible for the hypotheses derived
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within this thesis. All data presented in this thesis was analysed by the candidate under
the guidance of Professor Stephen Touyz and Dr Margaret Charles.

Manuscripts: The candidate was responsible for the conceptualisation and the
interpretation of the data and was the principle author of the manuscripts presented in this
thesis, under the supervision of Professor Stephen Touyz.
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CONTENTS

Abstract………………………………………………………………………………….3
Overview………………………………………………………………………………...4
Acknowledgements……………………………………………..………………………5
Preface…………………………………………………………………………………..7
List of Tables…………………………………………………………………………...16
List of Figures………………………………………………………………………….19
Publications and Presentations Arising from the Research…………………………21
List of Abbreviations…………………………………………………………………..23

Chapter 1 INTRODUCTION TO THE EATING DISORDERS 24

1. 1 Anorexia Nervosa: Core Features…………………………………………………24
1.2 Bulimia Nervosa: Core Features…………………………………………………..27
1.3 Eating Disorders Not Otherwise Specified: Core Features………………………..30
1.4 Assessment………………………………………………………………………...31
1.4.1 DSM-IV Classification…………………………………………………..31
1.4.2 Assessment Instruments………………………………………………….34
1.5 Comorbidity of Mental Disorders …………………………………………………36
1.5.1 Mood Disorders…………………………………………………………..37
1.5.2 Substance-Abuse Disorders………………………………………………37
1.5.3 Personality Disorders……………………………………………………..37
1.6 Treatment…………………………………………………………………………...39
1.6.1 Anorexia Nervosa………………………………………………………...39
1.6.2 Bulimia Nervosa………………………………………………………….41
1.6.3 Eating Disorder Not Otherwise Specified………………………………..43

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1.7 Outcome…………………………………………………………………………….44
1.7.1 Anorexia Nervosa………………………………………………………...45
1.7.2 Bulimia Nervosa………………………………………………………….47
1.7.3 Eating Disorder Not Otherwise Specified………………………………..48
1.8 Summary……………………………………………………………………………48

Chapter 2 INTRODUCTION TO THE ANXIETY DISORDERS 50

2.1 Panic Disorder and Agoraphobia……………………………………………...……51
2.2 Specific Phobia ……………………………………………………………..…...…56
2.3 Social Phobia ………………………………………………………………………58
2.4 Obsessive Compulsive Disorder ……………………………………………...……60
2.5 Post Traumatic Stress Disorder……………………………………………………..62
2.6 Generalised Anxiety Disorder………………………………………………………67
2.7 Assessment……………………………………………………………….…………69
2.7.1 DSM-IV Classification ………………………………………..…………69
2.7.2 Assessment Instruments ………………………………………………….70
2.8 Comorbidity of Mental Disorders ………………………………………………….70
2.8.1 Mood Disorders…………………………………………………………..70
2.8.2 Substance Abuse Disorders……………………………………………….71
2.8.3 Personality Disorders……………………………………………………..71
2.9 Treatment…………………………………………………………………………...72
2.10 Summary……………………………………………………………………………75

Chapter 3 LITERATURE REVIEW: THE COMORBIDITY 77
OF EATING DISORDERS AND ANXIETY
DISORDERS – A REVIEW

The comorbidity of eating disorders and anxiety disorders: a review…………………...78
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