Anorexia Nervosa

Anorexia Nervosa is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Restriction of energy intake leading to significantly low weight in the context of age, sex, developmental trajectory, and physical health, with intense fear of weight gain and body image disturbance. Significantly, low weight is defined as weight that is less than minimally normal/expected.
  • Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), divides anorexia into two types:
    • Restricting type: not engaged in binge eating or purging behaviors for last 3 months
    • Binge eating/purging type: regularly engages in binge eating or purging behaviors (last 3 months)
  • System(s) affected: cardiovascular, endocrine, metabolic, gastrointestinal, nervous, reproductive
  • Severity of anorexia nervosa (AN) is based on BMI (per DSM-5):
    • Mild: BMI ≥17 kg/m2
    • Moderate: BMI 16.00 to 16.99 kg/m2
    • Severe: BMI 15.00 to 15.99 kg/m2
    • Extreme: BMI <15 kg/m2

Epidemiology

  • Predominant age: 13 to 20 years
  • Predominant sex: female > male (10:1 female-to-male ratio)

Incidence
8 to 19 women/2 men per 100,000 per year

Prevalence
  • 0.9% in women (0.3% in young females)
  • 0.3% in men (higher in gay and bisexual men)

Etiology and Pathophysiology

  • Complex relationship among genetic, biologic, environmental, psychological, and social factors that result in the development of this disorder
  • Subsequent malnutrition may lead to multiorgan damage.
  • Serotonin, norepinephrine, and dopamine neuronal systems are implicated.

Genetics
  • There is evidence of higher concordance rates in monozygotic than in dizygotic twins.
  • First-degree female relative with eating disorder increases risk 6- to 10-fold.
  • One genome-wide significant locus identified for AN on chromosome 12

Risk Factors

  • Female gender
  • Adolescence
  • Body dissatisfaction
  • Perfectionism
  • Negative self-evaluation
  • Academic pressure
  • Severe life stressors
  • Participation in sports or artistic activities that emphasize leanness or involve subjective scoring: ballet, running, wrestling, figure skating, gymnastics, cheerleading, weight lifting
  • Type 1 diabetes mellitus
  • Family history of substance abuse, affective disorders, or eating disorder

General Prevention

Prevention programs can reduce risk factors and future onset of eating disorders.

  • Target adolescents and young women 15 years of age or older.
  • Encourage realistic and healthy weight management strategies and attitudes.
  • Promote self-esteem.
  • Reduce focus on thin as ideal.
  • Decrease co-occurring anxiety/depressive symptoms and improve stress management.

Commonly Associated Conditions

  • Mood disorder—major depressive disorder
  • Anxiety disorders—social phobia, obsessive-compulsive disorder, posttraumatic stress disorder
  • Substance use disorder
  • High rates of cluster C personality disorders

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