Anorexia Nervosa

Anorexia nervosa is an eating disorder marked by self-imposed starvation and inappropriate dietary habits due to a morbid fear of weight gain and disturbed perception of body shape and weight. Patients have strikingly low BMI and diverse physiological and psychological complications. The condition is most commonly seen in adolescent girls. Treatment consists of psychotherapy (CBT) and patient hospitalization for intensive care and management of complications. Pharmacotherapy has a limited role.

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Overview

Definition

Anorexia nervosa is an eating disorder characterized by self-imposed starvation and inappropriate dietary habits due to an intense fear of weight gain and disturbed perception of body shape and weight.

Epidemiology

  • Common in young women aged 15–25 years 
  • Prevalence: approximately 1%
  • Women:men ratio: 3:1
  • Patients in professions that stress thinness, such as ballet dancers, athletes, and models, are frequently affected.
  • Highest death rate of any mental illness (5%–20%)

Pathophysiology

Complex interaction between biological, psychological, and social factors:

  • Sociocultural factors:
    • Media influence on excessive need to be thin
    • Cultural norms, excessively emphasizing thinness
  • Genetic factors: anorexia nervosa more likely in monozygotic than dizygotic twins
  • Environmental factors: Interpersonal relationships may affect eating habits.
  • Psychological factors:
    • Low self-esteem
    • Perfectionism
    • Impulsivity
    • OCD
  • Neurobiological factors:
    • Abnormalities in brain areas (corticolimbic circuits, dorsal striatum) involved in appetite and habitual behavior 
    • Abnormalities in dopamine and serotonin neurotransmitters 

Clinical Presentation

Anorexia nervosa affects almost all body systems and can present with a variety of symptoms and signs.

Symptoms

  • Difficulty concentrating and making decisions
  • Depressed mood and anxiety 
  • Headaches
  • Fainting or dizzy spells
  • Lethargy
  • Cold intolerance (decreased thyroid hormones)
  • Epigastric pain, gastroparesis, constipation

Signs

  • Emaciation
  • Hypotension, bradycardia, arrhythmias
  • Hypothermia
  • Dry skin, dehydration, lanugo (body hair/thin hair)
  • Breast atrophy
  • Physical signs consistent with self-induced vomiting: 
    • Swelling of the salivary glands
    • Dental caries
    • Scars or calluses on the hand from contact with the teeth (Russell sign)
  • Peripheral edema, edema around the eyes, abdominal distension
  • Amenorrhea 

Lab findings

  • Low iron, folate, or B12 levels (anemia)
  • Cytopenias
  • Serum electrolyte abnormalities due to recurrent vomiting (low potassium, calcium, magnesium, and phosphate)
  • Disturbances in albumin (low albumin indicate a chronically low protein intake)
  • Elevated liver enzymes
  • Urinalysis showing increased sedimentation rate
  • Low luteinizing hormone (LH) and follicle-stimulating hormone (FSH) (secondary amenorrhea) 
  • Hypercholesterolemia
  • Disruption of thyroid hormone level

Clinical imaging

  • ECG: shows sinus bradycardia
  • DEXA scan: decreased bone mineral density due to insufficient calcium, phosphate, and vitamin D in diet 
  • Imaging may be required to rule out malignant causes of weight loss.

Complications

  • Myocardial atrophy
  • Mitral valve prolapse
  • Pericardial effusion
  • Osteoporosis
  • Gastroparesis
  • Amenorrhea, infertility (functional hypothalamic amenorrhea due to low levels of LH and FSH)
  • Growth disturbances

Diagnosis

Criteria

Diagnosis is clinical, based on observed criteria:

  • Restricted dietary habits resulting in significantly low body weight
  • Intense fear of gaining weight
  • Perceived disturbance in body weight and shape
  • Symptoms must be present for at least 3 months.

Subtypes

  • Restricting type: characterized by excessive starvation (weight loss is accomplished primarily through dieting, fasting, and/or excessive exercise) 
  • Binge-eating/purging type: characterized by the use of drugs (laxatives, diuretics), induced vomiting, and excessive exercise as a means to reduce weight 

Severity

  • Mild: BMI 17–18.49 kg/m2
  • Moderate: BMI 16–16.99 kg/m2
  • Severe: BMI 15–15.99 kg/m2
  • Extreme: BMI < 15 kg/m2

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Management and Prognosis

Management

Treatment involves a combination of psychotherapy and pharmacotherapy.

  • Psychotherapy:
    • A comprehensive therapeutic approach is recommended. 
    • CBT is the mainstay of treatment.
    • Family therapy is also recommended, especially for those patients who reside with their families.
  • Pharmacotherapy:
    • Limited role
    • Olanzapine may be indicated in some cases (helps patients to gain weight) 
    • Antidepressants can also help patients to gain weight (e.g., paroxetine or mirtazapine).

Consider hospitalizing patients with:

  • Heart rate < 40/min
  • Blood pressure < 80/60 mm Hg
  • Cardiac dysrhythmia
  • Cardiovascular, hepatic, or renal compromise requiring medical stabilization
  • Severe dehydration
  • Serious medical complications of malnutrition (e.g., electrolyte imbalance, hypoglycemia, or syncope)
  • Suicidal ideation with plan or attempt
  • Body mass index < 15 kg/m2 or ideal body weight < 70%

Refeeding syndrome:

  • Constellation of metabolic disturbances that may occur due to refeeding of malnourished patients who are persistently starved.
  • Sudden increase in caloric intake causes an increase in insulin production.
  • Increase in insulin causes a sudden shifting of fluid and electrolytes into cells.
  • Marked electrolyte disturbances (hypophosphatemia), seizures, delirium, cardiac complications (cardiopulmonary failure), rhabdomyolysis
  • Aggressive nutrition without good monitoring can be fatal.

Prognosis

  • With timely treatment, most of the complications (except for osteoporosis) may be reversible.
  • One of the highest mortality rates among the psychiatric disorders
  • Those with restricting type are less likely to recover than those with binge-eating/purging type.

Differential Diagnosis

  • Bulimia nervosa: an anxiety-driven eating disorder defined by recurrent episodic binge eating paired with recurrent inappropriate compensatory behavior (inducing vomiting, laxative abuse, excessive exercising). Patients with this condition may have normal or even elevated BMI and are more likely to seek help. Treatment involves a combination of CBT and SSRIs.
  • Binge-eating disorder: an eating disorder marked by recurrent episodes of binge eating without inappropriate compensatory behavior, resulting in fluctuating body weight. Episodes occur at least once a week for 3 months. Treatment consists of a combination of psychotherapy and pharmacotherapy.
  • Rumination disorder: repeated regurgitation of food, which may be re-chewed, re-swallowed, or spit out, and which is not due to a general medical condition (e.g., GERD). Treatment involves multiple CBT techniques, including biofeedback psychotherapy, as well as medication, when appropriate (e.g., proton pump inhibitors).

References

  1. Kessler RC, et al. (2013). The prevalence and correlates of binge eating disorder in the World Health Organization World Mental Health Surveys. Biol Psychiatry. 73(9), 904–914. https://pubmed.ncbi.nlm.nih.gov/23290497/
  2. Keel PK, McCormick L. (2010). Diagnosis, assessment, and treatment planning for anorexia nervosa. In Grilo CM, Mitchell JE (Eds.). The Treatment of Eating Disorders: A Clinical Handbook, The Guilford Press, New York. p.3.
  3. Westmoreland P, Krantz MJ, Mehler PS. (2016). Medical Complications of Anorexia Nervosa and Bulimia. Am J Med. 129(1), 30–37. https://pubmed.ncbi.nlm.nih.gov/26169883/
  4. da Silva JSV, et al. (2020). Parenteral Nutrition Safety and Clinical Practice Committees, American Society for Parenteral and Enteral Nutrition. ASPEN Consensus Recommendations for Refeeding Syndrome. Nutr Clin Pract. 35(2), 178–195. https://pubmed.ncbi.nlm.nih.gov/32115791/
  5. Sadock BJ, Sadock VA, Ruiz P. (2014). Kaplan and Sadock’s synopsis of psychiatry: Behavioral sciences/clinical psychiatry (11th ed.). Chapter 15, Feeding and Eating Disorders. Philadelphia, PA: Lippincott Williams and Wilkins. pp. 509–532.
  6. Westmoreland P. (2017). Feeding and eating disorders. Retrieved May 27, 2021, from https://doi.org/10.2310/im.13038
  7. Westmoreland P. (2018). Clinical management of feeding and eating disorders. Retrieved May 27, 2021, from https://doi.org/10.2310/im.13039

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