Bulimia Nervosa
Christopher G. Fairburn
Zafra Cooper
Rebecca Murphy
Introduction
Origins of the concept
The history of the diagnosis bulimia nervosa begins as recently as 1979. It was in this year that Russell published his now seminal paper ‘Bulimia nervosa: An ominous variant of anorexia nervosa’(1) in which he described 30 patients (28 women and 2 men), seen between 1972 and 1978, who had three major features in common. First, they had recurrent episodes of uncontrolled overeating; second, they regularly used self-induced vomiting or laxatives as means of weight control; and third, they had a morbid fear of becoming fat. Russell described many other features shared by these patients, including a history of anorexia nervosa (present in 80 per cent), the presence of severe depressive symptoms, and the fact that in most cases their body weight was in the healthy range. He noted that the disorder tended to run a chronic course and that it was ‘extremely difficult to treat’. Finally, he suggested that this clinical picture should be viewed as a syndrome, distinct from anorexia nervosa, and he proposed the term ‘bulimia nervosa’.
It is difficult to exaggerate the importance of Russell’s paper. Its greatest contribution was perhaps its prescience in that it crystallized out from among the range of eating disorders seen in clinical practice a subgroup of patients that was just starting to become more common; it identified its central features; and it gave it an appropriate name.
Events since 1980
Events gathered pace in the 1980s. In 1980 a syndrome termed ‘bulimia’ was included in DSM-III.(2) This was intended to denote the type of patient that Russell had described, although its diagnostic criteria proved to be overly inclusive. In 1987, the criteria were refined and brought more in line with Russell’s original concept. The syndrome was also renamed bulimia nervosa.(3) Also in the early 1980s evidence mounted that bulimia nervosa might be common and this led to a spate of studies of its prevalence. At the same time reports were published describing the successful treatment of these patients, the two most promising approaches being a specific form of cognitive behaviour therapy and the use of antidepressant drugs. By the mid-1980s, both treatments had been tested in the first of what has become a large series of controlled trials.
Classification and diagnosis
The classification of the eating disorders and their principal diagnostic criteria are shown in Table 4.10.2.1. Bulimia nervosa is one of the two main eating disorders recognized in DSM-IV and ICD-10, the other being anorexia nervosa (discussed in Chapter 4.10.1). In addition, in DSM-IV there is a residual category termed ‘eating disorder not otherwise specified’. This is reserved for eating disorders of clinical severity that do not meet the diagnostic criteria for anorexia nervosa or bulimia nervosa.(6) In ICD-10, various eating disorder categories other than anorexia nervosa and bulimia nervosa are recognized (for example, atypical anorexia nervosa, atypical bulimia nervosa, overeating associated with other psychological disturbances), although these concepts have never been adequately defined or differentiated.
The relationship between the three DSM-IV diagnoses is represented diagrammatically in Fig. 4.10.2.1. The two overlapping inner circles represent anorexia nervosa (the smaller circle) and bulimia nervosa (the larger circle) respectively, the area of potential overlap being that occupied by those people who would meet the diagnostic criteria for both disorders but for the rule that the diagnosis of anorexia nervosa trumps that of bulimia nervosa (see Table 4.10.2.1). Surrounding these two circles is an outer circle which defines the boundary between having an eating disorder, a state of clinical significance, and having a lesser, non-clinical, eating problem. It is this boundary that demarcates what is, and is not, an eating disorder. Within the outer circle, but outside the two inner circles, lies eating disorder not otherwise specified (eating disorder NOS).
In DSM-IV a new eating disorder diagnosis was proposed termed ‘binge eating disorder’. It is designed to denote an eating problem characterized by recurrent binge eating in the absence of the extreme weight-control behaviour seen in bulimia nervosa. Since binge eating disorder is a provisional diagnostic concept, it is currently an example of eating disorder NOS.
The two schemes for classifying eating disorders encourage the view that anorexia nervosa and bulimia nervosa are distinct clinical states. Consideration of their clinical features and course over time does not support this.(7) Binge eating disorder aside, patients with anorexia nervosa, bulimia nervosa, and eating disorder NOS have
many features in common, most of which are not seen in other psychiatric disorders, and studies of their course indicate that patients migrate between these diagnoses over time: indeed, temporal migration is the norm rather than the exception. This temporal movement, together with the fact that the disorders share the same distinctive psychopathology, has led to the suggestion that the current diagnostic scheme is a poor reflection of clinical reality and that common ‘transdiagnostic’ mechanisms may be involved in the maintenance of eating disorder psychopathology.(8)
many features in common, most of which are not seen in other psychiatric disorders, and studies of their course indicate that patients migrate between these diagnoses over time: indeed, temporal migration is the norm rather than the exception. This temporal movement, together with the fact that the disorders share the same distinctive psychopathology, has led to the suggestion that the current diagnostic scheme is a poor reflection of clinical reality and that common ‘transdiagnostic’ mechanisms may be involved in the maintenance of eating disorder psychopathology.(8)
Table 4.10.2.1 Classification of eating disorders and their principal diagnostic criteria. | ||||||||||||||||||||||||||||||||||||||||
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 Fig. 4.10.2.1 A schematic representation of the relationship between anorexia nervosa, bulimia nervosa, and eating disorder NOS (Reprinted from Fairburn, C.G. and Bohn, K. Eating disorder NOS (EDNOS): an example of the troublesome “not otherwise specified” (NOS) category in DSM-IV, Behaviour Research and Therapy, 43, 691-701, copyright (2005), with permission from Elsevier). |
Clinical features
The great majority of patients with bulimia nervosa are female and most are in their 20s (although the age range is between 10 and 60 years). In considering the psychopathology of the disorder, a distinction may be drawn between its ‘specific’ and ‘general’ features. The former comprises features that are largely peculiar to eating disorders (for example, self-induced vomiting, the over-evaluation of shape and weight), whereas the latter consists of features seen in other psychiatric conditions (for example, depressive symptoms). The clinical features of bulimia nervosa are similar in men and women and in those with and without a history of anorexia nervosa.
Specific psychopathology
(a) Dieting and binge eating
The eating habits of patients with bulimia nervosa are characterized by strict dieting punctuated by repeated episodes of binge eating (see Fig. 4.10.2.2). The dieting is extreme and it is governed by multiple self-imposed dietary rules. These rules tend to be applied to all aspects of eating, including when to eat, what to eat, and how much to eat. As a result, the food eaten (when not binge eating) is restricted in quantity and range.
Recurrent episodes of ‘binge eating’ interrupt this dieting. (The term binge eating denotes discrete episodes of eating that have two characteristics: first, an unusually large amount of food is eaten,
given the circumstances; and second, there is a sense of loss of control at the time. Some patients with eating disorders have similar episodes of uncontrolled overeating that do not involve the consumption of objectively large amounts of food. These episodes are sometimes referred to as ‘subjective binges’ although technically speaking they do not meet the definition of a ‘binge’.) The frequency and regularity of the binge eating varies. Some patients have episodes almost every day, whereas in others the episodes are intermittent. In DSM-IV, it is specified that the binges should occur on average at least twice a week, but this is an arbitrary figure that has little discriminatory value. Among those patients in whom the binge eating is frequent, the binges have few, if any, obvious triggers, although there may be circumstances under which binge eating is more likely (for example, when alone at home). Among patients in whom the binge eating is less frequent, the binges often have clear precipitants. These tend to be of three overlapping types: first, there is breaking a personal dietary rule (for example, exceeding a daily calorie-limit or eating a banned food); second, there are situations which intensify concerns about shape and weight (for example, receiving an adverse comment about appearance); and third, there is the occurrence of negative moods (often as a result of interpersonal events). All three undermine the maintenance of strict dietary control.
given the circumstances; and second, there is a sense of loss of control at the time. Some patients with eating disorders have similar episodes of uncontrolled overeating that do not involve the consumption of objectively large amounts of food. These episodes are sometimes referred to as ‘subjective binges’ although technically speaking they do not meet the definition of a ‘binge’.) The frequency and regularity of the binge eating varies. Some patients have episodes almost every day, whereas in others the episodes are intermittent. In DSM-IV, it is specified that the binges should occur on average at least twice a week, but this is an arbitrary figure that has little discriminatory value. Among those patients in whom the binge eating is frequent, the binges have few, if any, obvious triggers, although there may be circumstances under which binge eating is more likely (for example, when alone at home). Among patients in whom the binge eating is less frequent, the binges often have clear precipitants. These tend to be of three overlapping types: first, there is breaking a personal dietary rule (for example, exceeding a daily calorie-limit or eating a banned food); second, there are situations which intensify concerns about shape and weight (for example, receiving an adverse comment about appearance); and third, there is the occurrence of negative moods (often as a result of interpersonal events). All three undermine the maintenance of strict dietary control.
 Fig. 4.10.2.2 A monitoring record illustrating the eating habits of a patient with bulimia nervosa. Asterisks are used to signify episodes of eating that were viewed by the patient as excessive. The column headed ‘V/L’ is for recording episodes of self-induced vomiting or laxative misuse. |
The amount of food eaten during binges varies, both from patient to patient and from episode to episode. Typical episodes involve the consumption of 1000 to 2000 kcal.(9) The food eaten generally comprises items that are otherwise being avoided. Thus binges tend to be composed of energy-dense, high-fat items such as chocolate, ice cream, and pastries. Binges come to an end as a result of the combined influence of exhaustion, extreme fullness, a diminution of the drive to eat, and the running out of food supplies. In about three-quarters of patients they are immediately followed by measures designed to counteract the effects of the overeating, the most common being self-induced vomiting and the taking of laxatives or diuretics.
The binges are a source of considerable distress. They magnify these patients’ fears of weight gain and fatness, and they may result in shame and self-disgust. For this reason most binges occur in private and are kept secret from others. It is the binge eating that eventually drives these people to seek help.
(b) Purging and other forms of weight control
In DSM-IV bulimia nervosa is subdivided into two types, a purging and non-purging type. In the purging type there is regular self-induced vomiting or the misuse of laxatives or diuretics, or both, whereas in the non-purging type such behaviour (‘purging’) is either not present or it is infrequent. The majority of patients seen in clinical practice have the purging form of the disorder and it has been the focus of most research.
Self-induced vomiting is the most common form of purging. In most patients it only takes place after binge eating. It is generally achieved by stimulating the gag reflex, using the fingers or some
other long object, although in more established cases it can be accomplished with no mechanical aid. The vomiting is repeated until patients think that they have retrieved all the food that they can. Patients get extremely distressed if they are unable to vomit after binge eating: indeed, if they foresee that they may not have the opportunity to vomit, they tend not to binge. A minority of patients also induce vomiting at other times, for example, following smaller episodes of overeating (subjective binges) or ordinary meals or snacks.
other long object, although in more established cases it can be accomplished with no mechanical aid. The vomiting is repeated until patients think that they have retrieved all the food that they can. Patients get extremely distressed if they are unable to vomit after binge eating: indeed, if they foresee that they may not have the opportunity to vomit, they tend not to binge. A minority of patients also induce vomiting at other times, for example, following smaller episodes of overeating (subjective binges) or ordinary meals or snacks.
The misuse of laxatives or diuretics is somewhat less common than self-induced vomiting. It takes two forms: one is to compensate for specific episodes of binge eating, like self-induced vomiting; and the other is as a general method of weight control (like dieting), in which case it is not tied to particular episodes of overeating. The number of laxatives or diuretics taken varies considerably, sometimes far exceeding the recommended dose.
None of these methods of purging is an effective method of weight control. Self-induced vomiting results in the retrieval of only about half to two-thirds of what has been eaten, the taking of laxatives has a minimal effect on food absorption, and diuretictaking has none. As a result, a significant proportion of each binge is absorbed.
The weight of most of these patients is in the healthy range (BMI between 20 and 25) due to the effects of the under-eating and overeating cancelling each other out. As a result they do not experience the secondary psychosocial and physical effects associated with maintaining a very low weight seen in anorexia nervosa.
Other forms of weight-control behaviour are practised by some patients, including over-exercising, the spitting out of food, and the taking of repeated enemas or saunas. Over-exercising is the most common of these, but it is not nearly as prominent or as obviously pathological as in anorexia nervosa. A minority of patients ruminate, that is, repeatedly regurgitate and re-chew food that has been eaten. They may then either re-swallow the food or spit it out. This behaviour is not well-understood.
In the non-purging type of bulimia nervosa there is no vomiting or misuse of laxatives or diuretics, or they occur infrequently. Instead, there is sustained and marked dietary restriction outside the binges. This is both a response to the binge eating and contributor to it, in that this type of eating increases the risk of further episodes. In all other respects the two subtypes of the disorder are similar.
(c) Attitudes to shape and weight
A characteristic set of attitudes to shape and weight is the other distinctive element of the specific psychopathology of bulimia nervosa. Equivalent attitudes are found in anorexia nervosa and most cases of eating disorder NOS. These attitudes are often described as the ‘core psychopathology’ of eating disorders. They are characterized by an overconcern with shape and weight in which there is a fear of weight gain and fatness that is generally accompanied by a pursuit of weight loss and thinness. Underlying this psychopathology is the tendency to judge self-worth largely, or even exclusively, in terms of shape and weight. Whereas it is usual to evaluate self-worth on the basis of perceived performance in a variety of domains of life (such as interpersonal relationships, work, sport, artistic ability, etc.), people with anorexia nervosa or bulimia nervosa evaluate themselves primarily in terms of their shape and weight. These attitudes and values constitute a good example of an overvalued idea.
Most features of bulimia nervosa can be understood as being secondary to these attitudes to shape and weight. The dieting, purging, and over-exercising are obvious secondary features. In addition, there are direct behavioural expressions of these concerns. For example, many patients repeatedly weigh themselves and scrutinize their appearance in mirrors. Others avoid any knowledge of their weight while being acutely sensitive about their appearance. Some avoid others seeing their body and some even avoid seeing it themselves. This can have a major impact on social and sexual relationships.
The concerns about shape and weight, and eating, have a major effect on others in the patient’s immediate environment. Meals are often times of tension and social events which involve eating may be avoided. The feeding of children may be affected(10) and their growth may be impaired(11) (see Chapter 9.3.6).
General psychopathology
General psychiatric symptoms are prominent in bulimia nervosa; more so than in anorexia nervosa. The nature of the comorbid symptoms also differs. Depressive features are particularly striking: indeed, the level of depressive symptoms in bulimia nervosa is equivalent to that seen in major depressive disorder. Anxiety symptoms are also encountered, many of which are directly related to the eating disorder; for example, there is often pronounced anxiety about eating in public. Obsessive-compulsive features are sometimes present, although they are less common than in anorexia nervosa. Similarly, social functioning is less impaired.
The depressive features of bulimia nervosa deserve special mention. In most patients the depressive features can be attributed to the presence of the eating disorder but in a subgroup there appears to be an independent coexisting, but interacting, clinical depression. Features suggestive of such coexisting clinical depressions include the following: recent intensification of depressive features (in the absence of any change in the eating disorder or the patient’s circumstances); pervasive and extreme negative thinking (i.e. broader in content than concerns about eating, shape, and weight); hopelessness in general (i.e. seeing the future as totally bleak, seeing no future, resignation); recurrent thoughts about death and dying; suicidal thoughts; guilt over events in the far past; a decrease in involvement with others over and above any impairment that already accompanied the eating disorder (e.g. ceasing to see friends); loss of interest in activities that had been pursued despite the eating disorder (e.g. ceasing to listen to music; ceasing to read newspapers or follow the news); and a decrease in drive and initiative.
These coexisting clinical depressions often go undetected since they are viewed as characteristic of bulimia nervosa. This is unfortunate for two reasons: first, they interfere with the treatment of the eating disorder; and second, they are readily treated with antidepressant drugs (unlike the secondary depressive features).
A minority of patients with bulimia nervosa have ‘impulsecontrol’ problems, such as the overconsumption of alcohol or drugs, or repeated self-harm (e.g. cutting). Some of these patients also meet diagnostic criteria for borderline personality disorder (see Chapter 4.12.2). The prevalence of such features varies according to treatment setting: they are unusual in community samples, whereas they are more frequent among patients seen in specialist treatment centres.
Much more common than frank personality disorders are two traits which are also seen in anorexia nervosa. The first is low self-esteem. This generally antedates the eating disorder, although it is often exaggerated by it. Many patients with bulimia nervosa describe longstanding doubts about their worth and ability, irrespective of their accomplishments. The second is perfectionism, that is, imposing on oneself inordinately high personal standards in a range of domains (for example, work, sport, personal conduct). Since many of these standards are unachievable, it is common for these patients to give long histories of viewing themselves as perpetually failing.
Physical features
There are few physical abnormalities in bulimia nervosa. Body weight is unremarkable in the majority of patients and thus the physical effects of starvation are rarely seen. Nevertheless, menstrual abnormalities or amenorrhoea are present in about a quarter of patients. These are likely to be secondary to the disturbed eating since they generally respond to the successful correction of the eating disorder. On laboratory testing endocrine abnormalities are sometimes encountered and these tend to be mild versions of those found in anorexia nervosa. Fertility appears not to be affected.
Frequent purging, and especially the combination of vomiting and laxative misuse, results in fluid and electrolyte abnormalities in some patients. These abnormalities are varied in nature but most often consist of some combination of hypokalemia, hyponatremia, and hypochloremia. The patients appear to accommodate to these abnormalities since medically serious complications (for example, cardiac arrhythmias) are much less common than might otherwise be expected given the laboratory findings. Some patients experience intermittent oedema particularly if there is a sudden decrease in the extent of their purging.
Localized physical abnormalities include erosion of the dental enamel (especially from the lingual surfaces of the front teeth) among those who have vomited for many years; traumatic calluses on the knuckles of the hand of those who use their fingers to induce the gag reflex (Russell’s sign); and enlargement of the salivary glands, especially the parotids, probably as a result of chronic inflammation. A small proportion of patients have raised serum amylase levels usually due to an increase in the salivary isoenzyme.
Relationship to other disorders
Anorexia nervosa and eating disorder NOS
Bulimia nervosa has many features in common with anorexia nervosa and eating disorder NOS, particularly the characteristic attitudes to shape and weight and the behaviour that arises directly as a result.(12) In most cases, bulimia nervosa is preceded either by frank anorexia nervosa (in about a quarter of cases) or an anorexia nervosa-like form of eating disorder NOS. While movement from bulimia nervosa to anorexia nervosa is unusual, progression on to some form of eating disorder NOS is common. Whether it is appropriate to view such patients as having recovered from one psychiatric disorder and developed another is a moot point: rather, it would seem more appropriate to view them as having a single evolving eating disorder.
There is some evidence of co-aggregation between bulimia nervosa, anorexia nervosa, and eating disorder NOS with there being increased rates of all three diagnoses among the relatives of probands with either condition.(13)
Obesity
Few patients with bulimia nervosa are overweight or have obesity. On the other hand there is evidence of raised rates of parental and premorbid obesity.(14) Obesity is an unusual sequel of the disorder although this may be because those at most risk of obesity are less likely to recover and so continue to suppress their weight.
Other psychiatric disorders
As noted above, depressive features are common in bulimia nervosa and they may antedate the eating disorder. The same is true of anxiety and anxiety disorders. Most family studies have found a raised rate of affective disorder among these patients’ relatives whereas little is known about the familial relationship between bulimia nervosa and the anxiety disorders.(15) There is a raised rate of alcohol and drug abuse among patients with bulimia nervosa and a raised rate among these patients’ relatives.(15) Substance abuse rarely antedates the eating disorder but this is to be expected given the age of onset of substance abuse disorders.
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