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What is the Relationship Between Anorexia Nervosa and Obsessive Compulsive Disorder?

Mariah Smith


It has long been recognized that there are similarities between Obsessive Compulsive Disorder (OCD) and Anorexia Nervosa. These similarities lie in the symptoms of the disorder. Many patients of both diseases report intrusive, fearful thoughts, a compulsive need to perform rituals, and an obsession with maintaining these rituals. In the case of anorexia nervosa these behaviors center on food and thinness whereas in OCD they are of a more general type.

Past research has indicated that there is a higher prevalence rate for OCD among anorexia nervosa patients then in the normal population. The lifetime prevalence for OCD has been found to be around 3%. Conversely, the comorbidity rate for OCD and anorexia has been reported to be between 6% and 33%! This leads one to hypothesis that there may be a relationship between OCD and anorexia nervosa. It is not clear yet, based on the present research, what this relationship is. But, there are many studies out there that try to examine the relationship as well as its underlying causes. In this literature review some of this research will be examined and some preliminary conclusions will be drawn. Finally, further research to explore this relationship will be proposed.

Anorexia Nervosa

Anorexia nervosa is a specific disorder defined in DSM IV. Several classifications must be met for a diagnosis of anorexia to be made. There must be a refusal by the patient to maintain a healthy body weight for their age and height. This behavior must eventually lead to a weight loss in which the body weight falls to less then 85% of the persons ideal body weight. Or the patient can refuse to gain any weight during periods of growth. In women that have begun menstruation, the absence of three or more periods consecutively is a qualifying factor of a diagnosis of anorexia.

Anorexia is also defined by a distorted body image. This is harder to define but the patient usually experiences an intense fear of gaining weight. There is also a distorted way in which the body is viewed. Patients that have lost more than 85% of their body weight still feel that they are too heavy and must continue to lose.

There are two subtypes of anorexia. The binge eating/ purging subtype does not seem to be linked to the ritualistic behavior of OCD. The restricting subtype is the one that has been found to have a high comorbidity with OCD. This subtype involves restrictive behavior to lose weight. The subject restricts their food intake and does not misuse laxatives or diuretics.

The treatment for anorexia has usually been counseling. Sometimes the starvation is so bad that the patients must be hospitalized and fed intravenously or through a nasogastric tube. When they are well enough, counseling is begun. This may be individual or family therapy. The treatment process usually spans several months to several years.

Obsessive Compulsive Disorder (OCD)

"OCD patients have a pattern of distressing and senseless thoughts or ideas- obsessions- that repeatedly well up in their minds. To quell the distressing thoughts, specific patterns of odd behaviors- compulsions- develop." (Gee & Telew, 1999)

The patients are usually aware that their thoughts are irrational but that does not stop them from experiencing the anxiety that these thoughts produce. The compulsive rituals, if preformed properly, are believed to protect the patient from the harm of these intrusive thoughts. Since many people have a slight amount of intrusive thoughts and ritualistic behavior for a diagnosis of OCD to be reached these behaviors must become very distressing and consume a large amount of the patient’s time.

The obsessive thoughts experienced by the patient vary but they are usually in the form of violent images. A person might imagine that they would be unable to stop themselves from harming or killing their loved ones. The compensatory behavior usually manifests itself in the form of checking, counting, and washing. ‘Checking’ involves the patient needing to see dozens of times that the stove is turned off, that the door is locked, or that the alarm clock is set correctly. ‘Washing’ is a need for the patient to wash their hands many times a day, usually after touching certain objects. ‘Counting’ involves counting many objects encountered during the day: stairs, lines in the sidewalk, or passing cars.

OCD has been successfully treated with a combination of medication and therapy. Zorloft and Prozac are two of the common drugs that have been used to treat this disease. These drugs block the reuptake of serotonin in the brain. The success of medication in the treatment of OCD shows that one of the causes of the disease is biological. There may be other causes.

A Case Study

One of the most intriguing studies is the case study of a 14-year old athlete diagnosed with both anorexia and OCD. The young subject began high school at the normal weight of 101 lbs. and a height of 65 inches. (Gee & Telew, 1999) She participated in track and basketball. Soon after beginning her freshman year she began to exercise compulsively. She also restricted her food intake. Over the course of the year her weight dropped to 93 lbs. Her parents sought to intervene in her destructive behavior. She participated in individual as well as family counseling. Despite seeing a dietician her weight continued to drop and she soon weighed about 84 lbs. She had been hospitalized and several times doctors had tried nasogastric tube feedings to bring her weight back up. These were unsuccessful because the patient would remove the feeding tube. Her weight had fallen to less then 75% of her ideal body weight. By the time she was 15, the patient was referred to a psychiatrist who realized that the patient was exhibiting signs of OCD. Further counseling uncovered a history of OCD symptoms as far back as the age of eight. These symptoms were very ritualistic involving counting and arranging objects. These rituals carried over into her relationship with food. She felt the need to arrange her food certain ways and wear certain clothes.

With this diagnosis of OCD, the psychiatrist began a treatment of 20 mg of Prozac a day. This was combined with behavioral therapy geared towards treating OCD. This treatment was very successful. Within a few months the patients weight had climbed back over 100 lbs. She was able to return to school and resume athletic competition. Her parents and loved ones also noticed personality changes of a much more pleasant nature. She maintained a regimen of 10 mg of Prozac a day with no relapse to anorexic behavior and only slight, periodic episodes of compulsive behavior.

This study is very interesting but it raises more questions then it answers. Further in the article it provides some background information on both OCD and anorexia but it doesn’t draw any conclusions. We, as readers, are left to draw our own conclusions and address our own questions. Is anorexia nervosa a symptom of obsessive compulsive disorder? Is this why the treatment of the patients OCD was successful where the treatment of her anorexia had not been. Are both of these diseases the result of some deeper underlying cause? This question is addressed in another study that involves genetic testing.

It is difficult to draw conclusions from a case study. It is easy to see that one cannot statistically base any findings on one subject. However it is a good starting point for beginning other related research.

A study of comorbidity

In an attempt to find if there was a relationship between OCD and anorexia Thiel, Zurger, Jacoby, and Schussler conducted a study of inpatients at an eating disorders clinic in Germany. The specific question posed by the researchers was whether concomitant OCD influences the treatment outcome of patients with anorexia or bulimia nervosa.

The 93 subjects in this study were all female and all diagnosed with anorexia (35%) or bulimia (65%). 37% of the patients in the study also met the DSM IV requirements for OCD based on the Yale-Brown Obsessive Compulsive Scale. This was the initial assessment for the patients.

A follow up assessment was conducted after 30 months. Three tests were administered to determine the mental and physical health of the patient. The first test was a personal interview that discussed the patients eating behavior as well as family and work life. The second test was the Eating Disorders Inventory, which requires the patient to rate themselves in several categories including drive for thinness, body dissatisfaction, perfectionism, and maturity fears. The final test administered in the follow-up was the Hamburg Obsession Compulsion Inventory Short-Form. This 72-item questionnaire tests for various kinds of obsessive and compulsive behavior. The follow up study tested 75 of the original women who had been analyzed. 39% of these women met the criteria for OCD.

The follow-up study showed that 38 women no longer fulfilled the requirements for anorexia or bulimia. The study found no significant difference between the eating disorder diagnosis and the eating behavior of the OCD group and the non-OCD patients. However, the study did find that the patients who were most improved in their obsessive compulsive behaviors were the ones who also showed the most improvement of their eating behaviors.

The study concludes by asking the pertinent questions: ‘Is there a connecting link or a common cause underlying both disorders?’ If there is a link is it biological or psychological? The researchers agree that obsessive-compulsive behavior may be ‘provoked or accentuated during the course of an eating disorder’ (Thiel, Zurger, Jacoby, and Schussler, 1998) In their concluding remarks the researchers mention the author Rothenberg who suggested that in today’s modern society eating disorders are just a form of obsessive compulsive behavior based on modern society’s value on thinness.

This study is valid because it reconfirms the idea that there is a link between OCD and anorexia. However, it does not find any significant difference between the behavior of patients with comorbidity and those with just an eating disorder. It also does not mention much about HOW the women were treated. Was their OCD treated? (those that had it) Did this take care of their anorexia? Were all the women treated in similar manner for their disorder or was treatment individualized to the patient. All of this information would have been relevant and helped in drawing more conclusions about the relationship between the diseases. As the study is, it merely supports what was suspected: that there is a relationship between OCD and anorexia.

Genetic Coding

This study began based on the hypothesis that OCD is attributed (at least some what) to a deficit in the impulse control of the neurotransmitter serotonin. This deficit may be one of the causes of many disorders to include: depression, alcoholism, anorexia, and bi-polar disorder. The researchers stated that previous research has found the enzyme tryptophan hydroxlase (TPH) is responsible for limiting the rate of serotonin synthesis in the brain.

The researchers drew a random sample from a population of alcoholics and a similar control group of ‘normal’ subjects. Each participant donated some DNA material for testing. The DNA was sampled for deviations that would clue researchers as to whether or not there was a gene that determined if a person would suffer from one of the mentioned disorders. The researchers did not find any conclusive evidence that a common flaw in the genetic makeup links anorexia and OCD.

This study was difficult to understand unless one has a degree in biology or chemistry. However it provided a ‘layman’s’ discussion of the research in the discussion section. This was sufficient to understand that their findings were inconclusive with respect to comorbidity of anorexia and OCD.

Discussion and Proposed Research

There definitely appears to be a relationship between anorexia nervosa and obsessive compulsive disorder. Unfortunately, research has not yet determined what it is. Although inconclusive, it seems that some important clues can be drawn that could be the stepping off point for more research. Based on the case study of the 14-year-old athlete, OCD seems to be the more dominant disease. Perhaps it manifests itself in the form of an eating disorder. The particular patient fears fatness and therefore suffers related intrusive thoughts which distort their body image and lead them to perform rituals surrounding food intake that alleviate somewhat the intrusive thoughts. This is just a hypothesis.

It has also been proposed that both of these diseases are symptoms of a larger disorder. If so, what is this disorder? How can it be treated? It is clear that more research must be conducted. Now that a relationship has been established it must be inspected more closely. I would propose a study in which only comorbid patients were examined. Half could be treated only for OCD and the other half only for an eating disorder. To better understand the results, this first study should only use therapy as a means of treatment. This may lend a better understanding of the ‘carrier’ disorder. Several similar studies would have to be conducted. OCD seems to usually be treated with a combination of medication and therapy whereas anorexia is mainly treated with therapy. It should be studied whether Prozac or a similar serotonin reuptake inhibitor would be successful at all in treating anorexia since these drugs have had a fair amount of success in treating OCD.

It is important that a relationship has been identified. Perhaps the understanding of the higher prevalence of OCD in anorexic patients will lead to the more successful treatment of these patients. If further studies are conducted that lead to a better connection between the two disorders, sufferers can be treated more efficiently.


Gee, Rebecca, Telew, Nicholas. Obsessive Compulsive Disorder and anorexia nervosa in a high school athlete: A case report. Journal of Athletic Training. 1999: 34:375-378

Han L, Nielsen D, Rosenthal N, Jefferson K, Kaye W, Murphy D, Altemus M, Humphries J, Cassano G, Rotondo A, Virkkunen M, Linnoila M, & Goldman D. No coding varient of the tryptophan hydroxylase gene detected in seasonal affective disoder, obsessive-compulsive disorder, anorexia nervosa, and alcoholism. Biological Psychiatry. 1999:45:615-619.

Thiel A, Zurger M, Jacoby G, & Shussler G. Thirty month outcome in patients with anorexia or bulimia nervosa and concomitant obsessive-compulsive disorder. The American Journal of Psychiatry. 1998: 155:244-249.


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