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Day # 144: Anorexia Nervosa Part 1

Today we will continue our current theme of eating disorders. Today's topic is anorexia nervosa. In part 1 we will cover an introduction, definitions, diagnostic criteria, epidemiology, and pathogenesis. In part 2 we will cover clinical pearls, physical complications, and treatment.

Today's Content Level: Beginner and Intermediate

Introduction 1

  • Anorexia nervosa (AN) is an eating disorder characterized by significantly low body weight and preoccupation with weight, body image, and being thin.

  • It involves an intense fear of gaining weight or behaviors that prevent weight gain such as restricting calories, excessive exercise, self-induced vomiting, using laxatives, and more.

  • The term, anorexia nervosa, comes from the Greek term for "loss of appetite" and a Latin word implying "nervous origin".

  • The authors of Kaplan and Sadock's describe AN as a syndrome of three essential criteria: The first is a self-induced starvation to a significant degree— a behavior. The second is a relentless drive for thinness or a morbid fear of fatness— a psychopathology. The third criterion is the presence of medical signs and symptoms resulting from starvation— a physiological symptomatology.

Diagnostic Criteria 2

  • Restriction of caloric intake relative to requirements.

  • Significantly low body weight (less than minimally normal in the context of age, sex, developmental trajectory, and physical health).

  • Intense fear of gaining weight or becoming fat OR persistent behaviors that prevent weight gain.

  • Disturbed body image OR undue influence of body weight/shape on self-evaluation OR lack of recognition of the seriousness of current low body weight.

  • Two main sub-types-> 1) Restricting type: Weight loss is achieved through restricting calories, fasting, and/or excessive exercise. Has not regularly engaged in binge-eating or purging behavior. 2) Binge-eating/purging type: Engages in eating binges followed by self-induced vomiting, and/or using laxatives, enemas, or diuretics. Some individuals purge after eating small amounts of food without binging.

  • Severity is specified based on BMI for adults and BMI percentile for children and adolescents. Mild = BMI ≥17. Moderate = BMI 16-16.99. Severe = BMI 15-15.99. Extreme = BMI <15. The level of severity may be increased to reflect clinical symptoms, degree of functional disability, or the need for supervision.

Epidemiology/Pathogenesis 3, 4, 5, 6

  • Lifetime prevalence of AN is 1% in females (studies vary: 0.5-4%) and <0.5% in men (studies vary: (0.1-1.3%). 12-month prevalence among young females is 0.4%.

  • As many as 5% of young women exhibit symptoms of anorexia but do not meet the full diagnostic criteria, and some studies show disordered eating behavior in 15% of adolescent girls in the United States.

  • Studies reflect approximately a 10:1 female to male ratio. Sex distribution is less skewed in children.

  • Most common age of onset is between 14-18 years old but can occur at any age. Some studies show peaks at 13-14 and 17-18 which is hypothesized to occur due to hormonal and environmental influences respectively.

  • Tends to be a chronic and relapsing illness, however the course is variable. Approximately 50% experience remission. Time to remission is 5-6 years.

  • AN has the highest mortality among psychiatric disorders. This is due to high rates of suicide (1 in 5 deaths occur by suicide) and medical complications such as cardiac or infectious causes.

  • As with most psychiatric disorders, the dominant theory suggests AN develops from a combination of genetic, biological, environmental, and psychosocial factors.

  • Risk factors include family history of eating disorders (strong genetic concordance), female gender, age (teenage years higher risk), neglect/abuse/trauma, living in industrialized countries (food is abundant and high social pressure to be thin), poor body image / low self-esteem, adverse perinatal and neonatal events, feeding or sleeping difficulties during infancy, and participation in sports or activities with an emphasis on weight/size or involve subjective judging and weight classes (gymnastics, ballet, modeling, running, cheerleading, figure skating, wrestling, etc.). Genetic correlations have been made between schizoaffective disorder and obsessive-compulsive disorder.

  • Certain psychodynamic theories and personality traits have also been associated: obsessive-compulsive personality traits, narcissism, difficulty with separation and autonomy, exaggerated values of control, achievement, and perfectionism.


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