Identifying the Core Symptoms of Bulimia Nervosa and Associated Anxiety and Depression Cheri Levinson, Stephanie Zerwas, Benjamin CALEBS, Kelsie Forbush, Hunna Watson, Hans Kordy, Sara Hofmeier, Michele Levine, Benjamin Zimmer, Markus MOESSNER, Christine Peat, Cristin Runfola, Marsha Marcus, Cynthia Bulik

What is at the CORE OF BULIMIA NERVOSA? Bulimia nervosa (BN) is characterized by symptoms of: binge eating and compensatory behavior overevaluation of weight and shape BN symptoms often co-occur with symptoms of anxiety and depression Which specific BN symptoms maintain BN psychopathology? How are these symptoms associated with symptoms of depression and anxiety? Fairburn, Cooper, & Shafran, 2003; Palister & Waller, 2008

Models of Psychopathology Latent variable theory often used to describe why mental disorders develop & persist Symptoms arise from a common cause BN is the cause that leads to each of these common symptoms. BN Fear of weight gain Binge eating Purging Avoidance of food Bollen, 2002; Borsboom et al., 2016; Clark & Watson, 1991; Eaton, 2015; Haslam, Holland, & Kuppens, 2012

Network theory proposes that symptoms of disorders cause each other Symptoms are part of a dynamic network which can produce, sustain, and underlie mental disorders These interact with each other to strengthen (or weaken) the disorder Fear of Weight Gain Avoidance of food Binge eating Purging Borsboom & Cramer, 2010; Borsboom & Cramer, 2013; Kendler, Zachar, & Craver, 2011

What can network analysis teach us? Determine the symptoms that are central to the BN psychopathology network Examine how symptoms of comorbid disorders interact with symptoms of BN

Focus interventions to target: Clinical Utility Reducing core symptoms in treatment should theoretically also decrease related symptoms Focus interventions to target: core symptoms−symptoms play a crucial role in the network comorbid symptoms that link between multiple disorders Hayes, Yasinski, Barnes, & Bockting, 2015

A network of BN symptoms: Current study Examined: A network of BN symptoms: Which symptoms are most central (i.e. core symptoms)? The networks of BN, depression, and anxiety symptoms: Which depression and anxiety symptoms are most strongly related to BN symptoms?

Participants 196 patients recruited for a clinical trial All patients had DSM-IV diagnosis of BN Primarily female (n = 187; 95.4%) European American (n = 165; 84.2%) Majority had comorbid depression and/or anxiety (n = 136; 69.4%)

Measures Eating Disorder Examination Binge eating, restriction, fears of fatness Short Evaluation of Eating Disorders Vomiting, purging, excessive exercise Beck Anxiety Inventory Scared, dizziness Beck Depression Inventory-II Sad, fatigue, self-dislike Bauer et al., 2005; Beck, Steer, & Brown, 1996; Fairburn & Cooper, 1993; Steer & Beck, 1997

Network analyses Partial Correlation Networks (Glasso Estimator) Explains how symptoms relate while also considering the impact of all other symptoms Bridge Symptoms Symptoms that link adjacent symptoms together and are theorized to be pathways that could causally connect symptoms or behaviors Centrality Measures Betweenness – number of times symptom is passed through Closeness – closeness to other symptoms in the network Strength – having many connections to other symptoms

Bulimia Nervosa Psychopathology Network BN Network

** ** ** BETWEENESS CLOSENESS STRENGTH **weight preoccupation **weight dissatisfaction ** Higher peaks on right side indicate higher centrality **highest centrality items **lose weight ** **fear weight gain **

BN AND anxiety Network Bulimia Nervosa & Anxiety Network

BETWEENESS CLOSENESS STRENGTH **weight preoccupation ** **unsteady **terrified ** **shape dissatisfaction Higher peaks on right side indicate higher centrality **highest centrality items ** **lose control ** **fear weight gain **choking ** ** **avoid eating

BN and depression network Bulimia Nervosa & Depression Network

BETWEENESS CLOSENESS STRENGTH **weight preoccupation ** **sad ** Higher peaks on right side indicate higher centrality **highest centrality items ** **irritable **fear weight gain ** **concentrate **

Core BN symptoms CONCLUSIONS fear of weight gain & overevaluation of weight and shape Bridge symptoms - connect anxiety or depression symptoms to BN Physical sensations: unsteady, fears of losing control, choking, difficulty concentrating may be bridge symptoms

Fear of weight gain is central to BN network Binge eating and purging on the periphery Treatments that focus on fear of weight gain may have maximal impact Weekly weighing Exposure

Physical sensations bridge BN & anxiety/depression Exaggerated insula response in eating disorders? Sensitivity to physical sensations Interoceptive Exposures Kim et al., 2012; Fassino, Pierò, Gramaglia, & Abbate-Daga, 2004; Klabunde et al., 2013; Oberndorfer et al., 2013

Data is cross-sectional – no causality Limitations Data is cross-sectional – no causality Limited measurement of each symptom Applying network analysis to psychopathology is new No fit indices No measures of reliability Limited by measures and symptoms chosen for the network

Future directions Does change in a core symptom produce changes in other network symptoms? Do symptom networks become less strong after treatment and with symptom remission?

Acknowledgments & Disclosures Dr. Bulik is a grant recipient and consultant for Shire Pharmaceuticals and has consulted for Ironshore. Dr. Marcus is on the Scientific Advisory Board of Weight Watchers International, Inc. Dr. Peat is recipient of a contract from RTI and Shire Pharmaceuticals and has consulted for Sunovion Pharmaceuticals, L.E.K consulting, and Nexus Global Solutions. Dr. Watson is supported by a research grant from Shire awarded to UNC-Chapel Hill. Dr. Zerwas has consulted for L.E.K consulting. This research was supported by a National Institute of Mental Health (NIMH) grant (R01MH080065), a Clinical Translational Science Award (UL1TR000083), and the Alexander von Humboldt-Stiftung. Dr. Zerwas is supported by a NIMH career development grant (K01MH100435). Drs. Peat and Runfola were supported by a NIMH post-doctoral training grant (T32MH076694). Dr. Runfola was supported by the Global Foundation for Eating Disorders (PIs: Bulik and Baucom; www.gfed.org). Benjamin Zimmer was supported by a Fellowship for Postdoctoral Researchers from the German Academic Exchange Service (DAAD). Dr. Bulik acknowledges support from the Swedish Research Council (VR Dnr: 538-2013-8864). We wish to honor the incredible contribution and legacy of our colleague Dr. Robert Hamer, who passed away in December 2015.