The diagnostic criteria for anorexia nervosa have evolved over the years. The criteria given below are from The Diagnostic and Statistical Manual of Mental Disorders DSM-IV.
Diagnostic criteria for Anorexia Nervosa
A. Refusal to maintain body weight at or above a minimally normal weight for age and height (e.g., weight loss leading to maintenance of body weight less than 85% of that expected; or failure to make expected weight gain during period of growth, leading to body weight less than 85% of that expected).
B. Intense fear of gaining weight or becoming fat, even though underweight.
C. Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
D. In postmenarcheal females, amenorrhea, i.e., the absence of at least three consecutive menstrual cycles. (A woman is considered to have amenorrhea if her periods occur only following hormone, e.g., estrogen, administration.)
Restricting Type: during the current episode of Anorexia Nervosa, the person has not regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas)
Binge-Eating/Purging Type: during the current episode of Anorexia Nervosa, the person has regularly engaged in binge-eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas.
A Critical Look at the Criteria
To understand why it is so easy for a person with a digestive disorder to be misdiagnosed as having AN, it is necessary to take a critical look at the diagnostic criteria of DSM-IV. If the anorexic patient fulfills all of these criteria, then AN is diagnosed. After that, generally little or no effort will be made to search for physical causes of appetite loss. Let's examine each part of the criteria:
Refusal to maintain body weight...... It is easy to interpret the refusal to eat as something the patient is purposely doing to achieve some sort of weight goal. Yet most anorexic patients just don't feel like eating. Of course, if you assume that the patient is in perfect health (besides being malnourished), then not eating appears to be a deliberate choice. It is not that simple. Physical illness can severely impact appetite,and also absorption. So to conclusively determine that the patient is consciously refusing to maintain their body weight within 15% of normal (this is also a subjective matter - see page on Body Mass Index), one has to eliminate every possibility of appetite loss due to disease. Some diseases that cause appetite loss, nausea, or malabsorption are very easy to diagnose, and usually the patient will know something's wrong. Others, especially chronic diseases, are not, and may require extensive diagnostic testing to identify.
Intense fear of gaining weight or becoming fat......The adjective "intense" is highly subjective. The majority of women are very conscious of their figures. This is not necessarily a bad thing. Almost everyone, male or female, who interacts socially with other people is somewhat self-conscious with regards to their appearance (most of us look in the mirror and comb our hair before we go to school or work).
This criteria is the one that is prone to making women much more likely to be misdiagnosed with AN than a man. Let's assume the prevalence of chronic digestive disorders is the same among men and women (this would be an incorrect assumption, as the prevalence of many diseases vary with gender). Because women in general are far more concerned about being overweight than men (men typically would like to be more muscular or stronger), they will be far more likely to fulfill this criteria.
Young women are far more likely to wear tight fitting clothes (example: "painted-on" jeans) and so will notice even slight fluctuations in weight or fluid retention. A young woman can become quite frustrated that she won't fit in her tight jeans for several days each month, and if this is due to fluid retention or bloating she may "feel" fat as well.
Just how "intense" does this fear of gaining weight have to be? If the patient doesn't at first acknowledge this fear, will the therapist try to persuade her to admit to this fear? Certainly, if the therapist believes that the diagnosis should be AN, the temptation to extract a confession of weight preoccupation will be very strong. Once the patient does admit to being concerned about her weight, will this fulfill the criteria?
Disturbance in the way in which one's body weight or shape is experienced....When we look at someone other than ourselves, we tend not to be as critical of their appearance as we are of our own. When we look in the mirror, we may focus on details of our appearance that we would not focus on with others. If we have a painful pimple on our forehead, we may focus our attention on it and even become distressed about it. Others may not even notice it. This is because we are far more conscious of self than of others.
We also can experience pain or discomfort that may make us overly conscious of certain parts of our anatomy. Such may be the case if a person has a digestive disorder that causes abdominal bloating and distension.
The discomfort of bloating can command the sufferer's attention, and if the cause of this condition is not recognized, it may be interpreted as fat. Certainly, abdominal distension can make you feel and look fat, and the inability to fit into clothes may be convincing evidence for some. Most eating disorder programs only monitor weight and height. They generally do not monitor waist size, nor abdominal distension. This distension may be transient, varying with diet and stage of digestion. They also generally do not monitor edema (water retention) and it's effects on the patient's interpretation of their body shape.
The therapist may ask the anorexic patient to choose from several frontal silhouettes of thin, medium build, and obese bodies, that which most closely resembles their own. If the patient chooses the obese silhouette, this may be interpreted as confirmation of distorted body image perception. Of course an emaciated, malnourished anorexic patient is not fat. But it is perfectly understandable that she may feel fat. And as she loses weight and becomes more emaciated, her stomach by comparison looks even bigger. This optical illusion can convince the anorexic patient that more stomach crunches are needed or that they have to lose more weight.
denial of the seriousness of the current low body weight.... The human body has an amazing ability to adapt to a wide range of conditions. This probably explains why the human species has survived for so long. Conditioning plays a key role in this adaptive response. If we lift heavy loads on a regular basis, our muscles grow bigger and stronger to handle the increased demand. If we take up jogging, our heart becomes stronger and more effiecient to more effectively handle the demands placed on it. Some people who start jogging may only be able to make it half way around the block at first, but through conditioning may be able to run a marathon after a year of training.
The adaptive response to starvation is a truly amazing phenomenon, one that has secured the survival of the species through many famines over the course of history (for more information on this, see the Starvation Response page). If malnutrition sets in gradually, over the course of a few months or a few years, the body gradually adapts to the new conditions. The malnourished person may still have energy, and not feel lethargic or sickly. You'll find that most anorexic individuals indeed have very high energy levels, despite being seriously malnourished. In fact, there may be a natural tendency to be hyperactive, as the brain, preoccupied with sourcing nutrition, makes an effort to provide every survival advantage. In terms of evolutionary biology, this hyperactive state would have increased the prospects of starving populations catching elusive game or travelling to an area with a better food supply. If the anorexic patient has a digestive disorder, they may find it impossible to eat, and yet be totally adapted to their advanced state of malnutrition as well as their digestive disorder. Due to this adaptive response, the patient may not realize the seriousness of their condition.
In postmenarcheal females, amenorrhea....it is pertinent to note that anorexia nervosa is the only psychiatric disorder with a physical symptom as one of the diagnostic criteria. This is another criteria that causes much confusion both among therapists and physicians. Many physicians interpret the cessation of menses as one more symptom of AN. However, it is not that simple.
Amenorrhea may have many causes, including hypothyroidism, adrenal tumor, congenital abnormalities, polycycstic ovary or ovarian tumor. These possible causes must be ruled out through diagnostic testing before a diagnosis can be made. Malnutrition or excessive exercise can also cause amenorrhea. If AN is suspected, the amenorrhea is normally assumed to be due to malnutrition. Of course, the malnutrition is usually assumed to be due to a willful refusal to eat, in other words, anorexia nervosa. You can see how these assumptions become dangerous, because a female with a digestive disorder may also refuse to eat and become malnourished, and experience amenorrhea.
You can see how the diagnostic criteria from DSM-IV are totally inadequate to rule out physical causes of anorexia. Symptoms and behaviors assumed to be associated with AN can all be caused by chronic digestive tract disorders. All criteria are too subjective and are very prone to misinterpretation. It is no wonder there has been such an explosion in the prevalence of anorexia nervosa. The psychiatric community must address these deficiencies with the utmost urgency to prevent further misdiagnoses.