Evaluating the DSM-5 Alternative Model of Personality Disorders for Obsessive-Compulsive Personality Disorder Jacqueline Liggett Research School of Psychology The Australian National University July 2018 A thesis submitted for the degree of Doctor of Philosophy (Clinical Psychology) of The Australian National University. © Copyright by Jacqueline Liggett 2018 All Rights Reserved ii iii Statement of Originality This thesis is submitted to The Australian National University in fulfilment of the requirements for the degree of Doctor of Philosophy (Clinical Psychology). The work presented in this thesis is, to the best of my knowledge, original, except as acknowledged in the text. I hereby declare that I have not submitted this material, either in full or part, for a degree at this or any other institution. Jacqueline Liggett 30 November 2017 iv v Thesis Style Statement This thesis has been prepared in a journal article compilation format. This format was deemed appropriate due to the continuity between research papers presented in the body of work. The following publications appear chronologically in the thesis body: Liggett, J., Carmichael, K. L. C., Smith, A., & Sellbom, M. (2017). Validation of self- report impairment measures for section III obsessive-compulsive and avoidant personality disorders. Journal of Personality Assessment, 99, 1-14. doi:10.1080/00223891.2016.1185613. Liggett, J., Sellbom, M., & Carmichael, K. L. C. (2017). Examining the DSM-5 section III criteria for obsessive-compulsive personality disorder in a community sample. Journal of Personality Disorders, 31, 1-20. doi:10.1521/pedi_2017.31.281. Liggett, J., Sellbom, M., & Bach, B. (2017). Continuity between DSM-5 section II and section III personality traits for obsessive-compulsive personality disorder. Clinical Psychology and Psychotherapy, 1-8. doi:10.1002/cpp.2147. Liggett, J., & Sellbom, M. (2018). Examining the DSM-5 alternative model of personality disorders operationalisation of obsessive-compulsive personality disorder in a mental health sample. Advance online publication. Personality Disorders: Theory, Research and Treatment. vi vii Acknowledgments My deepest gratitude to Associate Professor Martin Sellbom, whose supervision over the past four years has been invaluable. I am incredibly grateful for your support, guidance and patience throughout this research project. It has been a privilege to learn from you, and I thank you for stretching me to make me a better researcher and psychologist. Many thanks also to Dr Boris Bizumic and Dr Linda Nicholson, whose support I have also valued. Thank you also to my collaborators, Kieran, Bo and Alex whose contributions I have greatly appreciated, and who I have enjoyed working with. To Mimosa, thank you for all the coffee, cheese, wine and laughter. You’ve made this journey a very entertaining one – I couldn’t have asked for a better office- mate or friend with whom to muddle through academic, professional, technical and ethical issues. Thank you, Luna, for keeping me company during the final stretch. And to Sam – the most important thank you of all. Without you I would not have survived this experience. Thank you for withstanding all of the stress, frustration and weariness. Your encouragement and endless amounts of support in every way imaginable has meant everything. I’m the luckiest person in the world to have had you by my side during this experience. This thesis is dedicated to you. This research was supported by an Australian Government Research Training Program scholarship. viii ix Abstract Obsessive-compulsive personality disorder (OCPD) is a severe mental health condition estimated to affect 2-7% of the population (American Psychiatric Association [APA], 2013; Grant et al., 2004), making it one of the most common personality disorders (PDs). It is currently operationalised by reference to several behavioural symptoms, including a preoccupation with details, rules and orderliness, over-conscientiousness, perfectionism, hoarding, excessive devotion to work and productivity, reduced capacity to express warmth and emotion, and mental and interpersonal control at the expense of flexibility, openness and efficiency (APA, 2013). The disorder has a long history in the clinical literature, being included in all versions of the Diagnostic and Statistical Manual of Mental Disorders (DSM) (APA, 1952|2013). Despite its history, prevalence and severity, OCPD has been the subject of only limited research. DSM-5 Section III (APA, 2013) includes a newly-developed hybrid dimensional-categorical diagnostic model for PDs: the Alternative Model of Personality Disorders (AMPD). The AMPD operationalises PDs using disorder-specific constellations of maladaptive personality traits and functional impairment. Studies assessing the personality traits relevant to OCPD have had inconsistent results, and research into the impairment profile of OCPD is limited. Additional research is required to refine the alternative model of OCPD. This research project aimed to help meet this need. Study One examined the validity of a newly-developed disorder-specific impairment scale for OCPD. Although the measure showed initial promise in its ability to measure-disorder specific impairment, results indicated that it may not be useful to maintain the distinction, made in the AMPD, between personality impairment in the self and interpersonal domains. Study Two evaluated the extent to which specific personality traits, and scores on the measure of OCPD-specific impairment from Study One, accounted for variance in scores on measures of traditional OCPD (as operationalised in DSM-5 Section II). Results showed x that three of the four AMPD traits, as well as two additional traits uniquely accounted for a large proportion of variance in a latent variable of traditional OCPD. Study Three examined the extent to which the trait criteria in the alternative model of OCPD corresponded with the traditional operationalisation of OCPD with a particular focus on the individual OCPD criteria, in a Danish clinical sample. Results revealed that the AMPD traits aligned only partially with the traditional conceptualisation of OCPD, and that additional traits may be relevant to further capture the nuances of this personality disorder. Study Four investigated the extent to which self-report and informant data of personality psychopathology correspond, the optimal trait profile for OCPD in the AMPD, and whether an OCPD-specific measure of impairment is more diagnostically useful than measures of general impairment in personality functioning. Results showed that self-report data moderately corresponded with informant data and that rigid perfectionism can be considered a core trait of OCPD. OCPD-specific impairment accounted for more variance in traditional OCPD than general measures of impairment. While additional research into the utility of the AMPD is required, taken together, these studies generally support the use of the hybrid dimensional-categorical approach in the assessment and diagnosis of OCPD. xi Contents Statement of Originality ................................................................................................ iii Thesis Style Statement .................................................................................................... v Acknowledgments ......................................................................................................... vii Abstract ........................................................................................................................... ix Contents .......................................................................................................................... xi List of Abbreviations and Symbols ............................................................................. xiii List of Figures ................................................................................................................ xv List of Tables ................................................................................................................ xvi Chapter One – Introduction ........................................................................................... 1 Obsessive-Compulsive Personality Disorder .......................................................... 3 Problems with the Traditional Model of Personality Disorders .............................. 6 The Development of an Alternative Model of Personality Disorders ..................... 9 Limitations of the Alternative Model of Personality Disorders ............................ 18 OCPD in the Alternative Model of Personality Disorders .................................... 22 Self-Report and Informant Measures of Personality ............................................. 26 Rationale for Research Program ............................................................................ 28 References.............................................................................................................. 31 Chapter Two – Study One ............................................................................................ 47 Abstract .................................................................................................................. 48 Introduction............................................................................................................ 49 Method ................................................................................................................... 56 Results ..................................................................................................................