RESEARCH ARTICLE Intrusive Thoughts in Obsessive–Compulsive Disorder and Eating Disorder Patients: A Differential Analysis Gemma García-Soriano 1 * , Maria Roncero 1 , Conxa Perpiñá 1,2 & Amparo Belloch 1 1 Universidad de Valencia, Valencia, Spain 2 CIBER Fisiopatología Obesidad y Nutrición (CIBERobn), Instituto Salud Carlos III, Spain Abstract The present study aims to compare the unwanted intrusions experienced by obsessive–compulsive (OCD) and eating disorder (ED) patients, their appraisals, and their control strategies and analyse which variables predict the intrusions’ disruption and emotional disturbance in each group. Seventy-nine OCD and 177 ED patients completed two equivalent self-reports designed to assess OCD- related and ED-related intrusions, their dysfunctional appraisals, and associated control strategies. OCD and ED patients experienced intrusions with comparable frequency and emotional disturbance, but OCD patients experienced greater disruption. Differences appeared between groups on some appraisals and control strategies. Intolerance to uncertainty (OCD group) and thought importance (ED group) predicted their respective emotional disturbance and disruption. Additionally, control importance (OCD group) and thought–action fusion moral (OCD and ED groups) predicted their emotional disturbance. OCD and ED share the presence of intrusions; however, different variables explain why they are disruptive and emotionally disturbing. Cognitive intrusions require further investigation as a transdiagnostic variable. Copyright © 2014 John Wiley & Sons, Ltd and Eating Disorders Association. Keywords intrusive thoughts; OCD; ED; transdiagnostic variable *Correspondence Gemma García-Soriano, Departamento de Personalidad, Evaluación y Tratamientos Psicológicos, Facultad de Psicología, Avda Blasco Ibáñez, 21, 46010 Valencia, Spain. Tel: 0034963983389. Email: Gemma.Garcia@uv.es Published online 5 March 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/erv.2285 Introduction Unwanted intrusions are spontaneous and discrete thoughts, images, or impulses that are experienced as being difficult to control and as interfering with ongoing activity (Clark, 2005; Rachman, 1981). These intrusions have been specifically studied in obsessive–compulsive disorder (OCD), although they have also been found in other mental disorders, such as post-traumatic stress disorder (Michael, Ehlers, Halligan, & Clark, 2005), depres- sion (Wahl et al., 2011; Wenzlaff, 2005), insomnia (Harvey, 2000), or eating disorders (ED) (Berry, Andrade, & May, 2007; Blackburn, Thompson, & May, 2012; Kavanagh, Andrade, & May, 2005; Perpiñá, Roncero, Belloch, & Sánchez-Reales, 2011; Rawal, Park, Mark, & Williams, 2010), with contents related to the specific disorder. Patients and community people with subclinical scores on ED symptom instruments, experience intrusions about food, diet, physical exercise, and appearance more frequently than the general population (Belloch, Roncero, & Perpiñá, 2012; Cooper, Todd, Woolrich, Somerville, & Wells, 2006, Perpiñá et al., 2011). These intrusions have been identified as relevant in the maintenance of ED (Cooper, Todd, & Wells, 2009). Although numerous studies have investigated the association between OCD and ED, the majority of them have focused on studying the presence of common characteristics (e.g. anxiety, depressive symptoms, and perfectionism) or co-morbid disorders (e.g. the presence of OCD in an ED patient) (e.g. Kaye et al., 2004; Milos, Spindler, Ruggiero, Klaghofer, & Schnyder, 2002; Rubenstein, Altemus, Pigott, Hess, & Murphy, 1995; Speranza et al., 2001). However, very few studies have examined the relationships between OCD and ED from a cognitive perspective (i.e. Freid, 2007; Lavender, Shubert, de Silva, & Treasure, 2006; Roncero, Perpiñá, & García-Soriano, 2011), for example, by specifically analysing intrusions. On the one hand, according to cognitive–behavioural OCD theories (e.g. Clark, 2004; Salkovskis, 1985), intrusions with different contents (aggression, sexuality/immorality, doubts, necessity to check, and contamination concerns, among others) develop into obsessions when these intrusions are appraised as highly disturbing and relevant, provoke negative emotional reactions, and lead to the individual’s need to neutralize or suppress them (e.g. through compulsions and other control strategies). However, these control and/or neutralizing strategies can be counterproductive. As a result, obsessions will continue to affect patients’ daily activity and quality of life. On the other hand, according to cognitive–behavioural models of ED, intrusions about food, body, weight, diet, physical exercise, and appearance can lead to emotional discomfort and the development of a series of behaviours (i.e. checking weight, doing exercise, binge eating, purging, or restricting intake) in an effort 191 Eur. Eat. Disorders Rev. 22 (2014) 191–199 © 2014 John Wiley & Sons, Ltd and Eating Disorders Association.