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Chapter: Essentials of Psychiatry: Eating Disorders

Anorexia Nervosa: Differential Diagnosis

Although depression, schizophrenia and obsessive–compulsive disorder may be associated with disturbed eating and weight loss, it is rarely difficult to differentiate these disorders from anorexia nervosa.

Differential Diagnosis


Although depression, schizophrenia and obsessive–compulsive disorder may be associated with disturbed eating and weight loss, it is rarely difficult to differentiate these disorders from anorexia nervosa. Individuals with major depression may lose significant amounts of weight but do not exhibit the relentless drive for thin-ness characteristic of anorexia nervosa. In schizophrenia, starva-tion may occur because of delusions about food, for example, that it is poisoned. Individuals with obsessive–compulsive disorder may describe irrational concerns about food and develop rituals related to meal preparation and eating but do not describe the intense fear of gaining weight and the pervasive wish to be thin that characterize anorexia nervosa.


A wide variety of medical problems cause serious weight loss in young people and may at times be confused with anorexia nervosa. Examples of such problems include gastric outlet ob-struction, Crohn’s disease and brain tumors. Individuals whose weight loss is due to a general medical illness generally do not show the drive for thinness, the fear of gaining weight and the increased physical activity characteristic of anorexia nervosa. However, the psychiatrist is well advised to consider any chronic medical illness associated with weight loss, especially when evaluating individuals with unusual clinical presentations such as late age at onset or prominent physical complaints, for exam-ple, pain and gastrointestinal cramping while eating.


Course and Natural History


The course of anorexia nervosa is enormously variable. Some in-dividuals have mild and brief illnesses and either never come to medical attention or are seen only briefly by their pediatrician or general medical physician. It is difficult to estimate the frequency of this phenomenon because such individuals are rarely studied.


Most of the literature on course and outcome is based on individuals who have been hospitalized for anorexia nervosa. Although such individuals presumably have a relatively severe illness and adverse outcomes, a substantial fraction, probably between one-third and one-half, make full and complete psy-chological and physical recoveries. On the other hand, anorexia nervosa is also associated with an impressive long-term mortal-ity. The best data currently available suggest that 10 to 20% of patients who have been hospitalized for anorexia nervosa will, in the next 10 to 30 years, die as a result of their illness. Much of the mortality is due to severe and chronic starvation, which eventu-ally terminates in sudden death. In addition, a significant fraction of patients commit suicide.


Between these two extremes are a large number of indi-viduals whose lives are impaired by persistent difficulties with eating. Some are severely affected maintaining a chronic state of semistarvation, bizarre eating rituals and social isolation; others may gain weight but struggle with bulimia nervosa and strict rules about food and eating; and still others may recover initially but then relapse into another full episode. There is a high fre-quency of depression among individuals who have had anorexia nervosa and a significant frequency of drug and alcohol abuse, but psychotic disorders develop only rarely. Thus, in general, in-dividuals either recover or continue to struggle with psychologi-cal and behavioral problems that are directly related to the eating disorder. It is of note that it is rare for individuals who have had anorexia nervosa to become obese.


It is difficult to specify factors that account for the vari-ability of outcome in anorexia nervosa. A significant body of experience suggests that the illness has a better prognosis whenit begins in adolescence, but there are also suggestions that pre-pubertal onset may portend a difficult course. It is likely that the severity of the illness (e.g., the lowest weight reached, the number of hospitalizations) and the presence of associated symptoms, such as binge-eating and purging, also contribute to poor out-come. However, it is impossible to predict course and outcome in an individual with any certainty.


Goals of Treatment


The first goal of treatment is to engage the patient and her or his family. For most patients with anorexia nervosa, this is chal-lenging. Patients usually minimize their symptoms and suggest that the concerns of the family and friends, who have often been instrumental in arranging the consultation, are greatly exag-gerated. It is helpful to identify a problem that the patient can acknowledge, such as weakness, irritability, difficulty concen-trating, or trouble with binge-eating. The psychiatrist may then attempt to educate the patient regarding the pervasive physical and psychological effects of semistarvation and about the need for weight gain if the acknowledged problem is to be successfully addressed.


A second goal of treatment is to assess and address acute medical problems, such as fluid and electrolyte disturbances and cardiac arrhythmias. Depending on the severity of illness, this may require the involvement of a general medical physician. The additional but most difficult and time-consuming goals are the restoration of normal body weight, the normalization of eating and the resolution of the associated psychological disturbances. The final goal is the prevention of relapse.





A common major impediment to the treatment of patients with anorexia nervosa is their disagreement with the goals of treat-ment; many of the features of their illness are simply not viewed by patients as a problem. In addition, this may be compounded by a variety of concerns of the patient, such as basic mistrust of relationships, feelings of vulnerability and inferiority, and sen-sitivity to perceived coercion. Such concerns may be expressed through considerable resistance, defiance, or pseudocompliance with the psychiatrist’s interventions and contribute to the power struggles that often characterize the treatment process. The psy-chiatrist must try to avoid colluding with the patient’s attempts to minimize problems but at the same time allow the patient enough independence to maintain the alliance. Dealing with such dilem-mas is challenging and requires an active approach on the part of the psychiatrist. In most instances, it is possible to preserve the alliance while nonetheless adhering to established limits and the need for change.


The initial stage of treatment should be aimed at reversing the nutritional and behavioral abnormalities (Figure 58.3). The intensity of the treatment required and the need for partial or full hospitalization should be determined by the current weight, the rapidity of weight loss, and the severity of associated medical and behavioral problems and of other symptoms such as depression. In general, patients whose weights are less than 75% of expected should be viewed as medically precarious and require intensive treatment such as hospitalization.


Most inpatient or day treatment units experienced in the care of patients with anorexia nervosa use a structured treatment approach that relies heavily on supervision of calorie intake by the staff. Patients are initially expected to consume sufficient cal-ories to maintain weight, usually requiring 1500 to 2000 kcal/day



in four to six meals. After the initial medical assessment has been completed and weight has stabilized, calorie intake is gradually increased to an amount necessary to gain 2 to 5 lb/week. Because the consumption of approximately 4000 kcal beyond mainte-nance requirements is needed for each pound of weight gain, the daily calorie requirements become impressive, often in the range of 4000 kcal/day. Some eating disorder units provide only food while others rely on nutritional supplements such as Ensure or Sustacal. During this phase of treatment it is necessary to moni-tor patients carefully; many will resort to throwing food away or vomiting after meals. Careful supervision is also required to obtain accurate weights; patients may consume large amounts of fluid before being weighed or hide heavy articles under their clothing.


During the weight restoration phase of treatment patients require substantial emotional support. It is probably best to ad-dress fears of weight gain with education about the dangers of semistarvation and with the reassurance that patients will not be allowed to gain “too much” weight. Most eating disorders units impose behavioral restrictions, such as limits on physical activ-ity, during the early phase of treatment. Some units use an ex-plicit behavior modification regimen in which weight gain is tied to increased privileges and failure to gain weight results in bed rest.


A consistent and structured treatment approach, with or without an explicit behavior modification program, is generally successful in promoting weight recovery but requires substantial energy and coordination to maintain a supportive and nonpunitivetreatment environment. In most experienced treatment units, parenteral methods of nutrition, such as nasogastric feeding or intravenous hyperalimentation, are only rarely needed. Nutri-tional counseling and behavioral approaches can also be effec-tive in helping patients expand their dietary repertoire to include foods they have been frightened of consuming.


As weight increases, individual, group and family psycho-therapy can begin to address other issues in addition to the dis-tress engendered by gaining weight. For example, it is typically important for patients to recognize that they have come to base much of their self-esteem on dieting and weight control and are likely to judge themselves according to harsh and unforgiving standards. Similarly, patients should be helped to see how the eating disorder has interfered with the achievement of personal goals such as education, sports, or making friends.


There is, present, no general agreement about the most useful type of psychotherapy or the specific topics that need to be addressed. Most eating disorders programs employ a variety of psychotherapeutic interventions. A number of psychiatrists recommend the use of individual and group psychotherapy us-ing cognitive–behavioral techniques to modify the irrational overemphasis on weight. Although most authorities see little role for traditional psychoanalytic therapy, individual and group psychodynamic therapy can address such problems as insecure attachment, separation and individuation, sexual relationships and other interpersonal concerns. There is good evidence sup-porting the involvement of the family in the treatment of younger patients with anorexia nervosa. Family therapy can be helpful in addressing family members’ fears about the illness; interventions typically emphasize parental cooperation, mutual support and consistency, and establishing boundaries regarding the patient’s symptoms and other aspects of his or her life.



Despite the multiple physiological disturbances associ-ated with anorexia nervosa, there is no clearly established role for medication. The earliest systematic medication trials in ano-rexia nervosa focused on the use of neuroleptics. Theoretically, such agents might help to promote weight gain, to reduce physi-cal activity and to diminish the distorted thinking about shape and weight, which often reaches nearly delusional proportions. Early work in the late 1950s and 1960s using chlorpromazine led to substantial enthusiasm, but two placebo-controlled trials of the neuroleptics, sulpiride and pimozide, were unable to establish significant benefits. In recent years interest has grown in taking advantage of the impressive weight gain associated with some atypical antipsychotics; however, no controlled data supporting this intervention have yet appeared. Despite the frequency of de-pression among patients with anorexia nervosa, there is no good evidence supporting the use of antidepressant medication in their treatment.


Unfortunately, although controlled trials have provided some evidence of benefit, the impact of cyproheptadine, an anti-histamine, in anorexia nervosa appears limited.


A large percentage of patients with anorexia nervosa re-main chronically ill; 30 to 50% of patients successfully treated in the hospital require rehospitalization within 1 year of discharge. Therefore, posthospitalization outpatient treatments are recom-mended to prevent relapse and improve overall short- and long-term functioning. Several studies have attempted to evaluate the efficacy of various outpatient treatments for anorexia nervosa including behavioral, cognitive–behavioral and supportive psy-chotherapy, as well as a variety of nutritional counseling inter-ventions. Although most of these treatments seem to be helpful the clearest findings to date support two interventions. For pa-tients whose anorexia nervosa started before age 18 years and who have had the disorder for less than 3 years, family therapy is effective, and for adult patients, cognitive–behavioral therapy reduces the rate of relapse. Preliminary information suggests that fluoxetine treatment may reduce the risk of relapse among patients with anorexia nervosa who have gained weight, but ad-ditional controlled data are required to document the usefulness of this intervention.


Refractory Patients


Some patients with anorexia nervosa refuse to accept treatment and thereby can raise difficult ethical issues. If weight is ex-tremely low or if there are acute medical problems, it may be ap-propriate to consider involuntary commitment. For patients who are ill but more stable, the psychiatrist must weigh the short-term utility of involuntary treatment against the disruption of a poten-tial alliance with the patient.


The goals of treatment may need to be modified for patients with chronic illness who have failed multiple previous attempts at inpatient and outpatient care. Treatment may be appropriately aimed at preventing further medical, psychological and social de-terioration in the hope that the anorexia nervosa may eventually improve with time.

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