Revision 2 for 'Anorexia nervosa'

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Anorexia nervosa

Anorexia nervosa is the most fatal psychiatric disorder characterized by distorted self-perception of body weight leading to starvation, obsession with remaining underweight and an excessive fear of gaining weight. One in five patients with anorexia die due to a complication of the disease.

Epidemiology

The lifetime prevalence of anorexia nervosa is 0.66 - 1.9% based on geographical location, with a higher prevalence in developed countries.

Females are ten times more likely to be diagnosed with anorexia nervosa compared to men.

The lifetime incidence of anorexia nervosa has increased from 0.1 to 5.4 per 100,000 over the last fifty years. In females aged 15-19, the incidence has increased from 56.4 to 109 per 100,000 person years 1.

Clinical features

The Diagnostic and Statistical Manual of mental disorders (DSM-5) recognizes the following criteria for the diagnosis of anorexia nervosa

  • Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than minimally expected.
  • Intense fear of gaining weight or of becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight.
  • 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 persistent lack of recognition of the seriousness of the current low body weight.

Along with these, numerous signs may be observed and they include (but are not limited to) the following

  • lanugo hair and/or alopecia
  • Amenorrhea (from suppression of the gonadal axis)
  • dental carries (from purging)
  • orthostatic hypotension or tachycardia
  • resting bradycardia
  • hilatosis
  • purpurae 2

Radiographic features

Nervous system

Complications include global cerebral atrophy, subacute combined degeneration of the cord (SCDC) due to Vitamin B 12 deficiency, wernicke's encephalopathy due to thiamine deficiency and alterations in the 5-HT system (observed on fMRI). For more information on CNS complications, please refer to the article Anorexia Nervosa (CNS).

Cardiovascular system

Left ventricular mass reduction (can be observed on plain film with reduced cardiothoracic ratio), mitral valve prolapse (MVP), reduced exercise tolerance and cardiac failure (including Takotsubo and ampulla cardiomyopathy) and are recognized complications 3

Gastrointestinal system

Gastric dilatation (visible on plain x ray), perforation and necrosis are possible complications from repeated purging and/or gastric ulcers. Others include esophageal perforation due to purging and liver failure due to autophagy. Patients may develop pancreatic pseudocysts and fibrotic pancreas. Superior mesenteric artery (SMA) syndrome has been reported due to loss of the fat pad between the SMA and the duodenum. Patients may have constipation and abnormal colonic motility 4.

Musculoskeletal system

Patients are more likely to be osteopenic due to low body mass, lack of vitamin D and calcium and lack of estrogen. Patients tend to have a shorter stature and multiple vertebral and extraspinal fractures with minimal stress. Bone marrow fat content has been reported to be higher than normal in patients with anorexia nervosa 5.

Respiratory system

There are reports of patients having diaphragmatic dysfunction, early onset emphysema (due to autophagy) and recurrent pulmonary infections (due to poor immune function) 6,7.

Treatment and prognosis

The treatment of anorexia is beyond the scope of this article, however, it must be highlighted that various forms of psychotherapy including cognitive behavioral therapy (CBT) and family-based treatment (FBT) are the mainstay of treatment. Medical management also includes re-feeding and correction of micro and macronutrient deficiencies. The prognosis depends on a number of factors. A good therapeutic relationship, absence of other co-morbid conditions like personality disorders, presence of a strong support system, use of olanzapine and early intervention are associated with good outcomes.

 

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