Paediatrics: Anorexia nervosa

Anorexia nervosa

Epidemiology

Anorexia nervosa is the third commonest chronic illness in teenage girls. Prevalence in the Western world is 70.5%. Whilst varying with age, a sex ratio of 9:1 (girls:boys) is fairly typical. Pre-pubertal cases are rare, but do occur. Bulimia nervosa is generally of youth onset.

Causes

Often unclear in individual cases; however, genetic pre-disposition, a perfectionist personality, and low self-esteem seem to be implicated. Dissatisfaction with weight and shape is relatively common in children as young as 8yrs and is presumably a vulnerability factor. The pathway into anorexia nervosa is through weight loss, either due to a desire to lose weight or for some other reason such as depression/anxiety or, some-times, viral illness.

Diagnostic criteria

·  Dietary restriction (may be accompanied by vomiting, exercise, laxative abuse, or other weight control methods) leading to significant and unhealthy self-induced weight loss (e.g. to less than 85% of expected body weight for height or age or a BMI < 17.5) or to stunting of expected growth.

·  Intense fear of gaining weight even when severely underweight.

·  Body image distortion with dread of fatness.

·  Amenorrhoea (may be p or s).

In younger teenagers anorexic thoughts may often be either absent or hidden, e.g. fear of becoming fat may be absent because they ‘know’ they can control their weight. Individuals who exhibit significant weight-losing behaviours, not explained by depression, a specific phobia, or physical ill-ness, may be referred to as having an atypical eating disorder.

Treatment

The evidence-base for treatment is small. Management of anorexia ner-vosa in children and young people requires a team effort and virtually all cases will require intensive treatment with more than one therapeutic mo-dality. The key to success in individual treatment is the engagement with the therapist rather than the type of therapy provided. Involvement of the family through family therapy seems to be important.

Treatment is likely to be lengthy and to involve attention to anorexic behaviours, to recognizing and not acting on anorexic thoughts and feel-ings, and to returning to aspects of normal function such as school and home life. It is far preferable to work collaboratively with the young per-son. At times compulsory treatment (requires use of the Mental Health Act) may be needed.

Clearly, correction of dangerous weight loss or its secondary complica-tions may be urgent. Patients who are unable or unwilling to manage ade-quate oral nutrition may need nasogastric feeding. In any rapid refeeding plan the risks of refeeding syndrome  should be remembered.

Prognosis

Anorexia nervosa is a serious psychiatric disorder that carries a signifi-cant risk of mortality as well as considerable morbidity. Although some cases of anorexia in children and young people are mild and resolve with-out intensive treatment programmes, many will go on into adult services with chronic eating problems. Whilst the quoted long term outcomes for anorexia generally accept that a third will recover full, a third will make a partial recovery and a third with have chronic symptoms, this is taking into account the lifetime course of the illness. The prognosis for teenagers is generally better than for adults with most making a full recovery. This can, however, take years, and an interim step may be to learn how to live with the illness rather than be controlled by it.

The risks to physical long term health are greater without early atten-tion to malnutrition and long term problems include:

·growth retardation;

·delayed or arrested puberty;

·reduced bone density;

·higher likelihood of low birth weight baby.

Risk factors for poorer outcome

·late onset;

·excessive weight loss;

·vomiting and purging as part of the clinical picture;

·poor social adjustment;

·poor parental relationships;

·being male;

·chronic course of illness.