Comorbidity of Anxiety Disorders with Anorexia and Bulimia Nervosa

Article Comorbidity of Anxiety Disorders With Anorexia and Bulimia Nervosa Walter H. Kaye, M.D. Objective: A large and well-character- sive disorder (OCD) (N=277 [41%]) and so- ized sample of individuals with anorexia cial phobia (N=134 [20%]). A majority of Cynthia M. Bulik, Ph.D. nervosa and bulimia nervosa from the the participants reported the onset of Price Foundation collaborative genetics OCD, social phobia, specific phobia, and Laura Thornton, Ph.D. study was used to determine the fre- generalized anxiety disorder in child- quency of anxiety disorders and to under- hood, before they developed an eating stand how anxiety disorders are related to disorder. People with a history of an eat- Nicole Barbarich, B.S. state of eating disorder illness and age at ing disorder who were not currently ill onset. and never had a lifetime anxiety disorder Kim Masters, B.S. Method: Ninety-seven individuals with diagnosis still tended to be anxious, per- anorexia nervosa, 282 with bulimia ner- fectionistic, and harm avoidant. The pres- Price Foundation Collaborative vosa, and 293 with anorexia nervosa and ence of either an anxiety disorder or an Group bulimia were given the Structured Clinical eating disorder tended to exacerbate Interview for DSM-IV Axis I Disorders and these symptoms. standardized measures of anxiety, perfec- Conclusions: The prevalence of anxiety tionism, and obsessionality. Their ratings disorders in general and OCD in particular on these measures were compared with was much higher in people with anorexia those of a nonclinical group of women in nervosa and bulimia nervosa than in a the community. nonclinical group of women in the com- Results: The rates of most anxiety disor- munity. Anxiety disorders commonly had ders were similar in all three subtypes of their onset in childhood before the onset eating disorders. About two-thirds of the of an eating disorder, supporting the pos- individuals with eating disorders had one sibility they are a vulnerability factor for or more lifetime anxiety disorder; the developing anorexia nervosa or bulimia most common were obsessive-compul- nervosa. (Am J Psychiatry 2004; 161:2215–2221) C linical and epidemiological studies have consis- mediated pathway toward the development of anorexia tently shown that the majority of people with anorexia nervosa and bulimia nervosa. nervosa or bulimia nervosa experience one or more anxi- Despite this wealth of data, many questions regarding ety disorders (1–3). Studies using trained interviewers and the nature of the relation between comorbid eating disor- standardized diagnostic instruments in clinical samples ders and anxiety disorders remain unanswered (1). Most have found that obsessive-compulsive disorder (OCD), clinical studies have investigated relatively small groups of social phobia, and specific phobia are the most common subjects with eating disorders and have lacked sufficient anxiety disorders in individuals with anorexia nervosa and statistical power to characterize comorbidity patterns of bulimia nervosa. Other anxiety disorders, such as post- the more uncommon anxiety disorders. In addition, few traumatic stress disorder (PTSD) and generalized anxiety studies have been sufficiently large to subtype subjects disorder, appear to be less common; however, they were with eating disorders accurately into clearly defined not routinely assessed in all studies. groups with anorexia nervosa, bulimia nervosa, or both Several studies have shown that, in most cases, the on- anorexia and bulimia. To our knowledge, no study has set of anxiety disorders precedes the onset of anorexia ner- compared patterns of comorbidity of anxiety disorders vosa or bulimia nervosa (4–6). Silberg and Bulik (7), using across these three well-defined diagnostic subcategories. twins, identified a common genetic factor that influences The Price Foundation has supported a multicenter, in- liability to anxiety, depression, and eating disorder symp- ternational collaborative study of the genetics of eating toms. This pattern of onset may simply reflect the natural disorders. This study has included a collection of affected course of the two disorders (i.e., the average age at onset of pairs consisting of probands with bulimia nervosa who some anxiety disorders is younger than the average age at have relatives with bulimia nervosa, anorexia nervosa, or a onset of anorexia nervosa), but it may also indicate that broad-spectrum eating disorder (8). The Price Foundation childhood anxiety represents one important genetically sample is sufficiently large and rigorously diagnosed to Am J Psychiatry 161:12, December 2004 http://ajp.psychiatryonline.org 2215 ANXIETY DISORDERS, ANOREXIA, AND BULIMIA enable separation of participants into clearly defined eat- Comparison Women From the Community ing disorder diagnostic subcategories. A comparison group of 694 healthy women were recruited by The goals of the present study were to 1) calculate the fre- local advertisement and matched with the eating disorder sub- quency of all types of anxiety disorders in a large, well-char- jects based on site, age range (except no comparison subjects under 18 years were included), ethnicity, and highest educational acterized eating disorder sample; 2) understand how anxi- level completed. They were 18–65 years old, primarily of Euro- ety disorders are related to factors such as state of eating pean ancestry, and at normal weight (lifetime body mass index disorder illness and age at onset; and 3) compare tempera- range=19–28). Comparison women were excluded if they had ment in subjects with eating disorders by lifetime anxiety medical, psychiatric, or alcohol or drug disorders or a first-degree disorders to determine whether personality phenotypes oc- relative with an eating disorder. Psychiatric and substance exclu- sions were defined by the presence of any “likely” axis I disorder cur when anxiety disorders are controlled. We hope that as assessed by the Structured Clinical Interview for DSM-IV these data will assist in identifying likely behavioral en- (SCID) Screen Patient Questionnaire—Extended (9). Also ex- dophenotypes in our attempts to identify the genetic un- cluded were women with a history of any substantial dieting, eat- derpinnings of anorexia nervosa and bulimia nervosa. ing disorder behaviors, or excessive concerns with weight or shape, as defined by a score of 20 or higher on the Eating Attitudes Test-26 (10). Comparison women completed the same battery of Method self-report personality and symptom measures as probands and provided blood samples for genetic analysis. Collaborative Arrangements Assessment Instruments This study was supported through funding provided by the Assessment instruments are described in greater detail else- Price Foundation under the principal direction of Walter H. Kaye where (8). Eating disorder symptom profiles and diagnoses of of the University of Pittsburgh and Wade Berrettini of the Univer- probands and affected relatives were determined by using a mod- sity of Pennsylvania (see reference 8 for details). This initiative ified version of the Structured Interview for Anorexic and Bulimic was developed through a cooperative arrangement among the Price Foundation, the University of Pittsburgh, and other aca- Disorders (11) and an expanded version of module H of the SCID demic sites in North America and Europe. The sites of collabora- (12). Lifetime major axis I anxiety disorder diagnoses were obtained by using the SCID; the Yale-Brown Obsessive Compulsive tive arrangement, selected on the basis of experience in the assessment of eating disorders and geographical distribution, Scale (13) was administered in conjunction with the OCD section included the University of Pittsburgh, Cornell University, Univer- of the SCID. Anxiety disorder diagnoses were made according to DSM-IV criteria. We classified individuals who were one symp- sity of California at Los Angeles, University of Toronto, University of Munich, University of Pisa, University of North Dakota, Univer- tom short of the threshold diagnosis for anxiety disorders to have sity of Minnesota, and Harvard University. Each site obtained in- probable diagnoses. Both individuals with threshold diagnoses and those with probable diagnoses were included. The defini- stitutional review board approval separately from its own institu- tions for probable anxiety disorder are available on request (from tion’s human subjects committee. Dr. Kaye). Participants completed the State-Trait Anxiety Inven- Phenotypic Assessment tory (14), the Frost Multidimensional Perfectionism Scale (15), and the Temperament and Character Inventory (16). Probands met the following criteria: 1) DSM-IV lifetime diagnosis of bulimia nervosa, purging type; 2) age between 13 and 65 Statistical Methods years; and 3) primarily of European descent. A current or lifetime All statistical analyses were completed by using SAS 8.0 (SAS/ history of anorexia nervosa was acceptable (some subjects had STAT software, version 8. SAS Institute, Cary, N.C.). Logistic re- both bulimia nervosa and anorexia nervosa). (For further details gression with the generalized estimating equation, which pro- see reference 8.) vides a chi-square value for testing significance, was used to cor- Affected relatives were biologically related to the proband, rect for nonindependence of the sample caused by inclusion of were 13 to 65 years old, and had at least one of the following life- family members and was applied to the data to compare rates of time

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