Description

• An eating disorder characterized by the restriction of food intake leading to significantly low weight with intense fear of weight gain and distorted perception of body weight and shape
• Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) divides anorexia into two types:
  • Restricting type: characterized by restricting intake of calories or extreme amounts of exercise without binge-eating and purging behaviors within the last 3 months
  • Binge-eating/purging type: regular engagement in binge intake or purging behaviors within the past 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; severe is <15 kg/m².

Epidemiology

Prevalence

• Estimated lifetime prevalence among U.S. adults of 0.5%
• Median age of onset age: 17 years
• Predominant sex: female > male (10:1 to 20:1 female-to-male ratio)

Etiology and Pathophysiology

• Complex relationships among genetic, biologic, environmental, psychological, and social factors that result in the development of this disorder
• Serotonin, norepinephrine, and dopamine neuronal systems are implicated.

Genetics

• Aggregates in families—11-fold risk among female relatives of a proband with the disorder
• Evidence of high concordance rates in monozygotic than in dizygotic twins
• GWAS study showing 8 loci exceeding genome wide significance on chromosomes 1, 3, 10, and 11.

Risk Factors

• Body dissatisfaction, negative self-evaluation
• Perfectionism, high parental demands, academic pressure, severe life stressors
• History of sexual or physical abuse or parental maltreatment
• 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 for adolescents and young women ≥15 years can reduce risk factors and future onset of eating disorders.

• 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