What is anorexia nervosa?

Anorexia Nervosa

Anorexia nervosa is a serious psychological eating disorder characterized by persistent restriction of food intake leading to significantly low body weight, intense fear of weight gain, and disturbance in the way one perceives their body weight or shape, with mortality rates among the highest of any psychiatric disorder. 1

Diagnostic Criteria

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), anorexia nervosa is diagnosed when a patient exhibits:

• Persistent restriction of energy intake leading to significantly low body weight
• Intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain
• Disturbance in the way one's body weight or shape is experienced, undue influence of body shape and weight on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight 1

Types:

• Restricting type
• Binge-eating/purging type 1

Epidemiology

• Peak age of onset: Early to mid-adolescence 1
• Prevalence: 0.3% lifetime prevalence in adolescent females 1
• Gender distribution: Historically 9:1 female-to-male ratio, but increasing numbers of males are being recognized, especially in younger age groups 1
• Increasing incidence: Notable increase in the incidence among 15-19 year-old girls 1
• Hospitalizations: 119% increase for children younger than 12 years from 1999 to 2006 in the US 1

Medical Complications

Anorexia nervosa can affect nearly every organ system in the body, with potentially life-threatening consequences:

• Cardiovascular: Bradycardia, hypotension, orthostatic changes, cardiac arrhythmias, QTc prolongation (responsible for 50% of deaths) 1, 2
• Endocrine: Amenorrhea, hypothalamic dysfunction, hormonal imbalances 3
• Gastrointestinal: Delayed gastric emptying, delayed small and large bowel transit 1
• Metabolic: Electrolyte abnormalities, particularly with purging behaviors 1
• Musculoskeletal: Osteopenia, premature fractures 2
• Neurological: Gray matter volume deficits that may persist after refeeding 2
• Hematologic: Anemia, leukopenia 1

Etiology

The cause of anorexia nervosa is multifactorial:

• Genetic predisposition: Family and twin studies suggest heritability 4
• Neurobiological factors: Aberrations in neuropeptides and neurotransmitters (including serotonin, dopamine, neuropeptide Y, and leptin) 3
• Psychological factors: Perfectionism, low self-esteem, body image disturbance 5
• Sociocultural influences: Emphasis on thinness, media portrayal of ideal body types 1

Assessment and Evaluation

The American Psychiatric Association recommends:

• Physical examination: Assessment of vital signs (temperature, resting heart rate, blood pressure, orthostatic pulse and blood pressure), height, weight, BMI, and physical appearance for signs of malnutrition or purging 1
• Laboratory assessment: Complete blood count, comprehensive metabolic panel including electrolytes, liver enzymes, and renal function tests 1
• Cardiac evaluation: Electrocardiogram for patients with restrictive eating disorders, severe purging, or those taking medications that prolong QTc intervals 1

Treatment Approach

Treatment requires a comprehensive, multidisciplinary approach:

1. Medical stabilization and nutritional rehabilitation:

   • Individualized goals for weekly weight gain and target weight 1
   • Addressing malnutrition and its physiological consequences

2. Psychotherapy:

   • For adults: Eating disorder-focused psychotherapy that normalizes eating behaviors, restores weight, and addresses psychological aspects like fear of weight gain and body image disturbance 1
   • For adolescents: Family-based treatment with caregiver involvement aimed at normalizing eating behaviors and restoring weight 1, 6

3. Pharmacotherapy:

   • Limited evidence for medication in anorexia nervosa
   • Fluoxetine may help prevent relapse in weight-restored patients 2

4. Level of care determination:

   • Outpatient treatment is preferred for medically stable patients 6
   • Inpatient care may be necessary for medical instability, severe malnutrition, or failed outpatient treatment 6

Prognosis and Challenges

• Long-term mortality rates may approach 20% 2
• Treatment resistance is common 5
• Early intervention improves outcomes 6
• Recovery can be prolonged, with risk of relapse 6

Anorexia nervosa requires early recognition and intervention by healthcare providers to reduce the severity of symptoms and health consequences. The high mortality rate and significant medical complications underscore the importance of prompt, comprehensive treatment.