Comorbidity Symptoms, Conditions, Behavior and Treatments Edited by Rhonda Brown Einar Thorsteinsson Comorbidity Rhonda Brown · Einar Thorsteinsson Editors Comorbidity Symptoms, Conditions, Behavior and Treatments Editors Rhonda Brown Einar Thorsteinsson Research School of Psychology School of Psychology Australian National University University of New England Canberra, ACT, Australia Armidale, NSW, Australia ISBN 978-3-030-32544-2 ISBN 978-3-030-32545-9 (eBook) https://doi.org/10.1007/978-3-030-32545-9 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Cover illustration: Gregory Davies/Stockimo/Alamy Stock Photo This Palgrave Macmillan imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Preface Collectively, as co-authors, we have extensive clinical and research expe- rience related to the various clinical disorders, symptoms, behaviour and biology covered in the book. Furthermore, as research collaborators, we can provide a unique perspective on the likely evolution and nature of disease comorbidity, which integrates biological, medical and psycho- logical perspectives. The book was written with an academic audience in mind, although other interested individuals may appreciate the explora- tion of possible mechanisms underpinning disease comorbidity. To be clear, this is not a self-help book that reflects upon the way in which people should live a better life or which reflects upon the way that we as individuals live our own lives. The stimulus for the book was research conducted by Laird Birmingham, Rhonda Brown and others, related to low body temper- ature and infection in anorexia nervosa patients, which later gave rise to discussions around the possible role played by body temperature in mediating some of the adverse health outcomes related to overweight/ obesity. However, more broadly, the co-authors have worked collec- tively, in several different research groups, to answer the following ques- tions related to disease comorbidity: What is causing the comorbidity v vi Preface between different medical and psychological conditions? What role (if any) is played by the shared (or overlapping) medical and psychological symptoms? Or is a common factor more likely to cause the co-occurrences? Finally, why is a similar profile of risk factors detected for a range of different but frequently comorbid illnesses and conditions? As argued in this book, there is a crucial need to more fully inte- grate a broader range of comorbid illnesses and conditions, and their often overlapping risk factors, into the same disease models; to arrive at a more complex real-world understanding of comorbid illness causa- tion. If such a clinical model could be developed, it might be used to test complex hypotheses related to the evolution and nature of disease comorbidity as well as evaluate potential new therapies. Finally, as co-authors, we wish to thank the various researchers and clinicians we have worked with over many years, who each have con- tributed to the evolution of the thoughts that are collectively advanced in this book. Canberra, Australia Rhonda Brown Armidale, Australia Einar Thorsteinsson Contents 1 Comorbidity: What Is It and Why Is It Important? 1 Rhonda Brown and Einar Thorsteinsson 1.1 What Is Comorbidity? 1 1.2 Why Is Comorbidity Important? 4 1.3 What Is the Cost of Comorbidity? 8 References 16 2 Models of Comorbidity 23 Rhonda Brown and Einar Thorsteinsson 2.1 Computational and Clinical Models of Concurrent Symptom Development 23 2.2 Sleep, Body Temperature, and Circadian Rhythm Function 30 References 36 vii viii Contents 3 Overweight/Obesity and Concurrent Disorders, Symptoms, Behaviour, and Body Temperature 43 Rhonda Brown and Yasmine Umar 3.1 Overweight/Obesity and Comorbid Disorders 43 3.2 Overweight/Obesity, Sleep Disorders, and Impaired Sleep 47 3.3 Overweight/Obesity, Disordered Eating, and Sleep 51 3.4 Overweight/Obesity, Disordered Eating, Sleep, and Body Temperature 58 References 64 4 Overview of the Comorbidity Between Medical Illnesses and Overweight/Obesity 79 Christopher J. Nolan 4.1 Medical Illnesses and Overweight/Obesity 80 4.2 Overweight/Obesity Comorbidities and Causal Linkages 91 4.3 Lessening the Burden of Comorbid Illnesses in Overweight and Obese Individuals 97 References 98 5 Comorbid Eating Disorders 115 C. Laird Birmingham 5.1 Anorexia Nervosa and Bulimia Nervosa 115 5.2 Eating Disorders and Medical Comorbidities 118 5.3 Eating Disorders and Anxiety and Mood Disorders 119 5.4 Can Comorbid Psychiatric Disorders Prevent Recovery from Eating Disorders? 121 5.5 Anorexia Nervosa, Body Temperature, Hyperactivity, and Clinical Outcomes 122 5.6 Body Warming to Treat Anorexia Nervosa, Hyperactivity, and Exercise Addiction 124 5.7 Other Medical Treatments for Anorexia Nervosa 126 References 129 Contents ix 6 Comorbid Psychiatric Illnesses 139 Einar Thorsteinsson and Rhonda Brown 6.1 Comorbidity Between Anxiety and Depressive Disorder 139 6.2 Relationships Between Stress, Depression, Anxiety, and Impaired Sleep 143 6.3 Risk and Protective Factors for Mental Ill-Health 145 6.4 Causal Models for the Development of Depression and Anxiety 149 References 161 7 Arousal States, Symptoms, Behaviour, Sleep and Body Temperature 179 Rhonda Brown and Einar Thorsteinsson 7.1 Arousal States and Elevated Body Temperature 179 7.2 Symptoms and Elevated Body Temperature 181 7.3 Exercise, Sleep, Affective Distress, Overweight/Obesity and Body Temperature 191 7.4 Behaviour Linked to Impaired Sleep and Elevated Body Temperature 197 References 202 8 Design, Statistical and Methodological Considerations: Comorbidity 221 Einar Thorsteinsson and Rhonda Brown 8.1 Methodological Approaches 221 8.2 Statistical Approaches 228 8.3 Overlapping Risk and Protective Factors 232 8.4 Other Research and Data-Handling Approaches 234 8.5 Summary 236 References 237 x Contents 9 Typing It All Together 241 Rhonda Brown and Einar Thorsteinsson 9.1 What Causes Comorbidity? 241 9.2 Comorbidity—Where to from Here? 248 9.3 Possible Existing, Repurposed, and Novel Treatments for Comorbid Illness 255 References 264