18 Eating disorders

Eating disorders traditionally include anorexia nervosa, bulimia nervosa, obesity and psychogenic vomiting. In the USA over recent years ‘binge eating disorder’ has been added to this list. There has also been more interest in the feeding disorders of infancy (see Chapter 16). These conditions have evoked intense medical interest because they exemplify the interaction between psychological and somatic symptomatology.

Definitions and diagnostic criteria

The ICD-10 and DSM-IV-TR requirements for diagnoses of anorexia nervosa and bulimia nervosa are shown in Table 18.1. Although anorexia nervosa and bulimia nervosa are distinguished in ICD-10, the other diagnoses of ‘atypical anorexia nervosa’ and ‘atypical bulimia nervosa’ recognize that it is by no means agreed that they are distinct entities. In ICD-10 it is noted that patients with anorexia nervosa can progress to bulimia nervosa and vice versa. The situation is further confused by the suggestion by some researchers that it is appropriate to distinguish between patients with anorexia nervosa who maintain a low weight by restricting caloric intake (‘restrictors’) and those who use restriction together with the symptoms also seen in bulimia nervosa (vomiting, purging, excessive exercise, use of appetite suppressants and/or diuretics).

Table 18.1 ICD-10 and DSM-IV-TR classifications of eating disorders

ICD-10 criteria for eating disorder (F50)

F50.0 Anorexia nervosa

• Body weight maintained 15% below expected for age and height

• Weight loss self-induced by

— restriction of intake

— self-induced vomiting

— self-induced purging

— excessive exercise

— use of appetite suppressants or diuretics

• Morbid dread of fatness (overvalued idea)

• Self-set low weight threshold

• Disturbance of endocrine function to produce amenorrhoea in women and loss of sexual interest and potency in men (in prepubertal onset there is delay of puberty and growth restriction)

F50.1 Atypical anorexia nervosa

• Some of the above, or

• Above features to a mild degree

F50.2 Bulimia nervosa

• Bingeing, with preoccupation with food and craving of the same

• Attempts to counteract excess calorie intake by

— self-induced vomiting

— self-induced purging

— alternating periods of starvation

— use of appetite suppressants, diuretics, thyroid preparations or, in diabetes, neglect of insulin treatment

• Morbid dread of fatness

• Self-set low weight threshold

• Possible history of anorexia nervosa or atypical anorexia nervosa

F50.3 Atypical bulimia nervosa

• Some of the above (but not if predominant symptomatology is depressive, when a diagnosis of depression should be made)

F50.4 Overeating associated with other psychological disturbances

• Obesity from overeating as a reaction to stressful events where the overeating is the predominant symptom

• Excludes distress because of obesity and drug-induced obesity

F50.5 Vomiting associated with other psychological disturbances

• Psychogenic vomiting where no other mental disorder is diagnosed (includes psychogenic hyperemesis gravidarum)

DSM-IV-TR classification for eating disorder (307)

307.1 Anorexia nervosa Specify type: Restricting type; binge eating/purging type

307.51 Bulimia nervosa Specify type: Purging type/non-purging type

307.50 Eating disorder NOS

Research criteria for binge eating disorder (classified under 307.50 above):

• Two or more episodes of binge eating over six or more months

• No recurrent purging, exercising or fasting

• Subjective sense of loss of control over binge eating

• PLUS three or more of the following signs. Eating

— more rapidly than usual

— large quantities of food when not physically hungry

— alone due to embarrassment

— until uncomfortably full and feeling self disgust

NOS, not otherwise specified.

In childhood, in addition to the feeding disorders, an extreme regression – termed ‘total refusal syndrome’ – has been identified in a very small group of children. In this, a child not only refuses to eat, but also declines all other activity, including appropriate elimination.

Anorexia nervosa and bulimia nervosa

Epidemiology

The incidence and prevalence of eating disorders depends as always on the definition used and the population being considered. Generally speaking, anorexia and bulimia nervosa are disorders of white Caucasian young adult females of a higher social class and above-average academic achievement. The peak incidence for anorexia nervosa is around the age of 18; that for bulimia nervosa is slightly higher.

The incidence of anorexia nervosa is about eight cases per 100 000 per year, being highest in 15–19-year-old females. A two-stage screening survey showed a prevalence of anorexia nervosa of between 0.2% and 0.8%, with a higher prevalence in the upper social classes. A study of UK adolescent schoolgirls showed a prevalence of 1–2%, with the higher prevalence in private-school girls. In addition to those with a full diagnosis, a further 5% in these surveys show some features of anorexia nervosa.

The incidence of bulimia nervosa is about 12 cases per 100 000 per year. The prevalence of bulimia nervosa by current criteria is about 1%, and between 2% and 4.5% of school and college girls. Until the 1970s bulimia nervosa was thought of as a subvariant of anorexia nervosa, and so some of the earlier studies deflated figures because of this.

The male:female ratio for anorexia nervosa is 1:10, although there have been some suggestions that the incidence of anorexia nervosa in males is increasing. In prepubertal patients the sex ratio, although still predominantly female, is not so marked. For bulimia nervosa the male:female ratio is between 1:5 and 1:10.

Anorexia has been reported in patients of all ethnic origins, but it is still relatively rare in non-Caucasians. It is said to be increasing in cultures such as Japan, which are becoming more ‘Westernized’.

The predominance of higher social classes is not so marked in young adolescents.

Definitions and epidemiology

• Eating disorders are most common in the young female population of the Western world.

• ICD-10 separates anorexia and bulimia nervosa as diagnostic entities, although there is a degree of overlap. Common to both is the ‘morbid dread of fatness’.

Clinical features

Although the weight loss in anorexia nervosa may be rapid (particularly in exacerbations and later relapses), family members or colleagues do not usually notice the initial onset. Thus, there is usually a history of at least several weeks and often several months prior to presentation. Individual patients will often report some particular remark or event that triggered their restrictive eating. In anorexia nervosa this may initially consist of limiting the types of food taken, with a progressive diminution in the range eaten. The individual may take to eating separately and secretively. Some patients may take a particular interest in the preparation and presentation of food to others. Individuals may take to wearing baggy clothes that have the effect of disguising their weight loss.

Paradoxically, certainly in the initial stages the young person may appear more cheerful and, to outsiders, be working extra hard in school or employment. Individuals describe a satisfaction in ‘control of weight’, which may explain the sense of confidence displayed.

With dieting and progressive weight loss, apart from increasing cachexia, various bodily changes occur as a direct result (Figure 18.1). Profound effects on hormonal balance return hypothalamic–pituitary–gonadal hormones to a prepubertal pattern. In prepubertal patients menarche is delayed. Effects on growth hormones produce a slowing or cessation of normal growth. If low weight is maintained for long enough, then final height may be stunted.

Figure 18.1 • Physical features associated with anorexia nervosa.

Amenorrhoea is usually related to reduction below a certain weight, although not infrequently it precedes the weight loss and may be maintained once an adequate weight is regained. In bulimia nervosa, and also in those with anorexia nervosa who use vomiting, purging, etc. to reduce their weight, a wide variety of menstrual irregularities can occur, including amenorrhoea.

In bulimia nervosa, extra medical complications occur in relation to the vomiting, purging and/or use of diuretics (Figure 18.2).

Figure 18.2 • Complications of vomiting, purging and diuretic abuse.

In anorexia nervosa, activity level is not a reliable indicator of the level of physical complications, as high levels of activity (including exercise, which may be used to further reduce weight) are often maintained at astonishingly low weights. Individuals may well increase their activity levels as their weight reduces.

At low weight sleep is disturbed, with difficulty settling, waking in the night and early morning wakening. Some weight-restrictive activities may be carried out secretly during periods of wakefulness.

It was recognized very early on that the use of the term anorexia (meaning loss of appetite) was a misnomer in anorexia nervosa, as the majority of sufferers will admit to extreme feelings of hunger and preoccupation with food, although this is often not admitted in the early stages to those close to them, and in some patients it is incorporated in a general pattern of denial of bodily sensation.

Low mood is very prominent in patients with anorexia nervosa and bulimia nervosa, particularly at low weight in the former. The symptoms can include the full biological array of symptoms (see Chapter 9), including sleep loss as mentioned above. In the majority of cases, the low mood resolves with return to normal weight. It must be noted that suicidal ideation and behaviour can occur in the context of this low mood. In bulimia nervosa, suicidal attempts and self-mutilation can be significant features.

Anorexia nervosa is distinguished from primary depressive disorder with its loss of appetite, loss of weight and low mood, and by the phenomenon variously described as ‘morbid fear of fatness’, ‘weight phobia’ and ‘body image disturbance’. Although various experiments using distorting mirrors etc. have been used to demonstrate the apparent ‘body-image’ disturbance as a perceptual distortion, this phenomenon may be more accurately characterized as an overvalued idea regarding ideal weight. Such beliefs may sometimes be held with almost delusional intensity. Studies of perceptual distortion are, at best, equivocal: it appears that overestimation of bodily dimensions is not pathognomonic of either anorexia or bulimia nervosa. In addition to the fear of fatness, there may also be self-denigration of bodily image and a low self-esteem. It is unclear whether this is related to ‘body image’ as such.

In bulimia nervosa, there is often a history of anorexia nervosa, and occasionally anorexia nervosa can be preceded by bulimic-type symptomatology. A typical cycle in bulimia nervosa is shown in Figure 18.3. It must be noted that there are very prominent psychological triggers and perpetuating factors that maintain the cycle.