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Comorbidity issues in Eating Disorders:

What is the relationship between obsessive-compulsive

Disorder and eating disorders?

 Cami Ridley

            If a person visited their doctor and described the following symptoms, what would you determine their diagnosis to be?  The woman is in her late teens and for the past six months she has been having problems with eating.  When she eats she must cut her food into very tiny pieces; these pieces are then counted and separated into foods that are healthy and those which may not be as healthy on the plate.  Once she has separated the foods she will not eat the unhealthy ones and discards them.  Next she arranges the food in rows on her plate before beginning to eat.  Once eating the food she only allows herself to have 7 bites of each food item so, as not to overindulge herself or stray from her set routine because she feels that something bad will happen if she exceeds this amount.  She then proceeds to eat each tiny piece separately chewing one hundred times for each bite.  This routine is repeated for each meal throughout the day and must be done in the same way each time.  When she is finished with a meal, which typically takes several hours, she goes about her daily activities as she does normally and exhibits no other strange behaviors. 

While it is obvious that the person described above has some issues with her eating behavior, what exactly is the nature of these issues?  On one hand, she may have an eating disorder.  She is meticulously concerned with the amount of food she is eating and the health value of each individual morsel of food.  She only allows herself to have a set number of bites and must chew them thoroughly for the fear that if she exceeds this set amount or style that something harmful will come to her.  These behaviors are only present when she is eating and have been observed in no other context, which would lead one to believe that the behavior is tied to eating specifically.  While these are behaviors that are sometimes present with an eating disorder, just simply the description of this routine does not in itself specify an eating disorder.  For diagnosis of anorexia or bulimia there must be an intense fear of gaining weight which is associated with this behavior.  This is not necessarily the case with this person.  Could the problem be obsessive-compulsive disorder?  Counting, checking, ordering and the presence of a strict routine are symptoms of obsessive-compulsive disorder as well.  Obsessions with checking the food, ordering the food and maintaining the routine could be the manifestations of this disorder as well.  It is apparent through this example that these two disorders may indeed have some degree of overlap in symptoms and problem behaviors. Eating disorders are complicated mental illnesses, which can manifest themselves in many different areas.  While the most obvious manifestations of an eating disorder are problems dealing with maintaining body weight and eating behavior, there are many factors, which underlie these problems with eating behaviors, which are not commonly publicized.  There are many behaviors that coincide with these bizarre eating behaviors that also deserve attention.  The issue of comorbidity and eating disorders is an important issue to tackle in terms of etiology as well as treatment.  When an eating disorder co-occurs with another mental disorder the way in which treatment may be implemented can be very different.  It is also interesting to look at the eating disorder in the context of the other mental illness to determine whether the two illnesses are distinct or whether one heavily influences the presence of the other.  This paper will look at the degree of overlap between obsessive-compulsive disorder and anorexia and bulimia.  By looking at the clinical research, which is being done, to investigate this linkage it may help us to better understand this relationship and the implications that it may have in terms of treatment and recovery.

In a study by Thornton and Russel (1997) they looked at the relationship between Obsessive-compulsive disorder (OCD) and all of the dieting disorders.  They wanted to test the hypothesis that OCD and the dieting disorders are ones which often occur together and try to establish this relationship in the literature.  In this study, they looked at the cases of sixty-eight inpatients that were in the hospital due to anorexia nervosa and bulimia nervosa.  Thirty-five of these patients had anorexia, and the remaining 33 had bulimia.  These cases were then analyzed using the DSM III-R Axis I and Axis II to determine whether they showed symptoms of obsessive-compulsive disorder, or obsessive-compulsive personality disorder.  They were also assessed for these two disorders using the Composite International Diagnostic Interview (CIDI), and the Personality Disorders Inventory (PDE).  They used the three measures to provide greater validity for the results and to tease out cases which indicate a personality disorder or those which indicate symptoms of the milder form of the disorder.  They found that 21% of the patient group met criteria for obsessive-compulsive disorder.  Within this group, 37% of these patients were diagnosed with anorexia nervosa compared to only 3% of those with comorbid OCD who had bulimia nervosa.  Through these measures they also wanted to determine whether the OCD problems predated the eating disorder or were developed after the onset of the eating disorder.  They found that in the majority of cases the OCD predated the eating disorder.  These results suggest that OCD is comorbid with eating disorders.  They also suggest that this relationship appears to be more strongly related to anorexia nervosa than bulimia nervosa.  It also appears in these results that in most cases the symptoms of OCD were present before the development of the eating disorder.  This study helps to establish a relationship between the two disorders and provides a basis for further research to investigate the nature of this linkage, and its particularly strong ties to anorexia nervosa.

Another study, by Bienvenu and colleagues (2000), investigated the relationship between OCD and a spectrum of disorders which tend to show some similar traits.  This spectrum includes body dysmorphic disorder, anorexia, bulimia, pathological grooming conditions, and other impulse control disorders such as pathological gambling and kleptomania.  The study sought to determine whether OCD was related more closely to any of the disorders in what it typically referred to as the obsessive-compulsive spectrum or whether these disorders are each inherently different in their own regard.  This study also sought to examine the prevalence of these disorders within families, to try and determine whether there is an underlying biological component between OCD and the other disorders in this spectrum.  They used 80 case and 73 control subjects to analyze these hypotheses.  They also used the data gathered from 343 case subject family members and 300 control family members to investigate the family linkages that may be behind the disorders.  Each of the subjects as well as the family members of the subjects were examined by psychiatrists, or psychologists using the Schedule for Affective Disorders and Schizophrenia-Lifetime anxiety version.  Two psychiatrists then independently evaluated the diagnoses made by the interviewing psychologists to make sure that the diagnoses were correct.  They found that 14% of the case patients who were diagnosed with OCD also had anorexia or bulimia.  They found that 41% of the case subjects have pathological grooming conditions, such as nail biting or nail picking.  While they did find relations between eating disorders and pathological grooming conditions and the occurrence of OCD they failed to find this relationship with any of the other obsessive-compulsive disorder spectrum disorders.  These finding suggest that eating disorders and OCD are indeed related.  This study also provides further evidence for the previous study’s finding that OCD symptoms were present before the onset of an eating disorder since the initial criterion for this study was a diagnosis of OCD.  This method was also very sound due to the personal interviewing and re-evaluation of the interviews by trained psychiatrists.  This study provides further evidence for this relationship as well as demonstrating that the relationship is specific to eating disorder and grooming conditions and not found in other disorders which share similar characteristics with OCD.

While these two studies demonstrate that there is a relationship between OCD and eating disorders, they do not address what the nature of this relationship may be.  A study by Bastiani and colleagues (1996) investigated which symptoms of OCD are most present in eating disorders.  To determine which OCD symptoms are more prevalent than others they took a sample of 18 patients with anorexia nervosa who were being treated at an inpatient clinic and 16 patients with OCD who were enrolled in outpatient therapy at the same institution and had them complete the Yale-Brown Obsessive-Compulsive scale.  By examining patients that were diagnosed with these two disorders separately and using a measure to test obsessive-compulsive tendencies they hoped to learn how the two disorders are related.  They found that patients in both groups had similar scores on the Yale-Brown inventory, with scores ranging from 19 to 22.  While the two groups tended to have similar scores they differed on the items of the questionnaire which they endorsed as true with relation to themselves.  Patients with OCD tended to endorse a high number of obsessive-compulsive tendencies in a wide range of areas from counting and checking to ordering.  They found those patients with anorexia, while they have similar scores, tended to endorse items dealing with symmetry and order only.  These results suggest that there are particular characteristics of OCD which are manifested in patients with eating disorders while the other facets of the disorder may not be very relevant.  This study helps to delineate which symptoms may be important to target in treatment and which ones may be important for the development of an eating disorder.

The next set of studies examines the treatment of bulimia or anorexia in those who are comorbid for OCD.  The two studies examine treatment outcomes relating to the symptomatology of eating disorders as well as the symptoms related to OCD.  The first study conducted by Thiel and colleagues (1998), examines the outcome data for patients with anorexia or bulimia and OCD at thirty months after hospitalization for an eating disorder.  The study looked at 75 female inpatients that met criteria for bulimia or anorexia and were patients in an inpatient treatment facility.  They looked at the patients first during the course of their inpatient treatment and then they followed the patients thirty months after they were discharged from the hospital.  They evaluated patients at both junctures using a diagnostic interview as well as the Eating-Disorder Inventory and the Hanburg Obsession-Compulsion Inventory.  They found that 51% of patients at the thirty-month follow-up no longer met criteria for anorexia or bulimia.  This improvement was not related to earlier presence of OCD.  Analysis demonstrated that significant improvement on at least 6 of the 8 Eating Disorder Inventory subscales regardless of the presence of OCD.  They also found that those who were the most recovered from their eating disorder at follow-up showed the greatest reduction in their obsessions and compulsions as well.  This study shows that those who receive greatest benefits from treatment also reduce their OCD behaviors.  This study also demonstrates that the treatment of an eating disorder is in significantly impaired by the presence of OCD.

Another study, which investigates OCD symptoms and treatment of eating disorders, examines bulimia specifically.  This is a unique study, performed by Von Ranson and colleagues (1999), in that it targets bulimia specifically, which is rare in the literature, and that the study examines symptoms both before and after treatment.  The study examines the relationship between OCD symptoms before and after inpatient treatment for bulimia nervosa.  This study used three cohorts, the first consisted of 31 patients who were currently being treated for bulimia, the second consisted of 29 women who had been recovered from bulimia nervosa for more than 1 year, and the third group was a control group of 19 comparison females.  All subjects completed the Yale-Brown Obsessive-Compulsive scale, which measures OCD symptoms and the items specifically dealing with core eating disorders were eliminated from the inventory before it was distributed to the subjects.  The results showed that both patient groups had significantly higher scores of the Inventory than did the control subjects.  The current bulimics scored around 13, the recovered bulimics scored around 7.9 and the control subjects showed scores of around 1.9.  Within the patient groups there was a marked difference in those who had undergone successful treatment to those who are currently undergoing treatment.  Even though the groups differed in terms of severity of behavior they recovered as well as current bulimics tended to endorse symptoms dealing with symmetry and exactness.  This study provides evidence that bulimics have symptoms of OCD as well as anorexics, which is the relationship that most literature focuses on.  It also demonstrates that OCD symptoms targeted in treatment such as exactness and symmetry are significantly improved in-patients who have recovered from bulimia.

The studies presented in this paper are indicative of the work that is being done investigating the relationship between OCD and the eating disorders.  The first two papers were good examples of the relationship that is found between patients either with an eating disorder that also have OCD or those with OCD who also have an eating disorder.  The second group of studies examined this relationship further to try and delineate which symptoms if any are more indicative of OCD in those patients who also have an eating disorder.  In the last group of studies the researchers built on the literature presented in the first paper and investigated the relationship in terms of treatment implications.  It appears that there is a strong link between OCD and eating disorders, especially OCD symptoms dealing with order, symmetry and exactness.  It is also evident that these symptoms diminish with successful treatment of an eating disorder.

While these studies provide evidence of the relationship between OCD and eating disorders, they also fail to target the possible nature of this relationship in terms of biological ties.  There is currently some new work being done investigating the role of serotonin in both OCD and eating disorders as this possible biological link.  These studies also all examine patients who are in inpatient treatment facilities.  These cases may be the most extreme cases of eating disorders and may present a biased sample who may be more at risk to develop OCD symptoms in the first place.  Despite these methodological flaws it seems clear that a relationship exists between OCD and eating disorders.  This research has provided a base for more exploration into the biological nature of the relationship, possible treatment modalities, which include treating symptoms of OCD and the evaluation of OCD symptoms as an important part in learning the true cause of an eating disorder.




















Bastiani, A. M., Althemus, M., Pigott, T. A., Rubenstein, C., Weltzin, T. E., & Kaye, W.

H. (1996).  Comparison of Obsessions and Compulsions in Patients with Anorexia Nervosa and Obsessive Compulsive Disorder.  Biological Psychiatry, 36, 966-969.

Bienvenu, O. J., Samuels, J. F., Riddle, M. A., Hoehn-Saric, R., Liang, K. Y., Cullen, B.

A.     M., Grados, M. A., & Nestaldt, G. (2000). The relationship of obsessive-compulsive disorder to possible spectrum disorders: Results from a family study. Biological Psychiatry, 48, 287-293.

Cumella, Edward J. (1999). Obsessive-Compulsive Disorder with Eating Disorders.

American Journal of Psychiatry, 156, 982.

Thornton, Christopher, & Russell, Janice. (1997). Obsessive Compulsive Cormorbidity in

the Dieting Disorders. International Journal of Eating Disorders, 21, 83-87.

Thiel, Andreas, Zuger, Markus, Jacoby, Georg E., & Schualer, Gerhard. (1998). Thirty-

month outcome in patients with Anorexia or Bulimia nervosa and concomitant obsessive-compulsive disorder. American Journal of Psychiatry, 155, 244-249.

Von Ranson, K. M., Kaye, W. H., Weltzin, T. E., Radhika, R., & Matsunaga, H. (1999).

Obsessive-Compulsive Disorder Symptoms before and after Recovery from Bulimia Nervosa. American Journal of Psychiatry, 156, 1703-1708.


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