Anorexia Nervosa

Basics

Description

  • An eating disorder characterized by the restriction of food intake leading to significantly low weight with intense fear of weight gain
  • 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 (last 3 months)
    • Binge eating/purging type: regularly engaged in binge eating or purging behaviors (last 3 months)
  • System(s) affected: nervous, cardiovascular, endocrine, metabolic, pulmonary, gastrointestinal, reproductive, ophthalmic, taste, and dermatologic
  • 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: 15 to 24 years
  • Predominant sex: female > male (10:1 to 20:1 female-to-male ratio)

Prevalence

  • 0.9–2.0% in women (1.1–3.0% in young females)
  • 0.1–0.3% in men (higher in gay and bisexual men)

Etiology and Pathophysiology

  • Complex relationships among genetic, biologic, environmental, psychological, and social factors that result in the development of this disorder
  • Parenting style that leads to high expectation may result in children struggle for control.
  • Serotonin, norepinephrine, and dopamine neuronal systems are implicated.

Genetics

  • 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, negative self-evaluation
  • Perfectionism, high parental demands, academic pressure, severe life stressors
  • History of sexual or physical abuse
  • Participation in sports or activities that emphasize leanness: ballet, figure skating, gymnastics, cheerleading
  • Type 1 diabetes mellitus
  • Family history of substance abuse, affective disorders, or eating disorders

General Prevention

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

  • Target adolescents and young women ≥15 years of age.
  • 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

  • Suicide, mood and anxiety disorders
  • Substance use disorder
  • Cluster C personality disorder

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