Description

• An eating disorder characterized by the restriction of food intake leading to significantly low weight (less than minimally normal/expected) in the context of age, sex, developmental trajectory, and physical health, with intense fear of weight gain and body image disturbance.
• 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 body mass index (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

• 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.

• 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