ICD-116B80	ANOREXIA NERVOSA Anorexia Nervosa
ICD-10F50.0	Anorexia nervosa
DSM-5-TRF50.0x	Anorexia Nervosa

1. Definition and nosology

Anorexia Nervosa (ICD-11: 6B80; DSM-5-TR: F50.0x) — a severe eating disorder characterized by significant low body weight due to restriction of food intake, intense fear of weight gain, and disturbance in body image. Among the highest mortality rates of psychiatric disorders.

2. History

• Morton R. (1689) — first clinical description.
• Lasègue C. (1873) and Gull W. (1874) — ‘anorexia hysterica’ and ‘nervous anorexia’.
• DSM-III (1980) — Official diagnosis.
• DSM-5 (2013) — amenorrhea criterion eliminated (diagnosis possible in males and premenarchal).

3. Epidemiology

• Lifetime prevalence: in females 0.9–4%, in males 0.3% (Smink F.R. reviews).
• Sex: 10:1 in females; but the diagnosis is often missed in male patients.
• Onset: adolescence (14–18 years); second peak in middle age.
• Mortality: lifetime 5–6%; half medical (cachexia, cardiac), half suicide (Arcelus J. et al. Arch Gen Psychiatry 2011 meta-analysis).
• Comorbidity: MDD, OCD, anxiety, BPD.

4. Aetiology and pathogenesis

• Heritability 50–60% (Bulik C.M. reviews).
• Neurobiological — reduced cognitive flexibility, reward circuit dysregulation, atypical response to hunger.
• Social-cultural factors — thinness ideal; social media influence.
• Personality - perfectionism, anxiety, family history of eating disorder.

5. Clinical features

• Food restriction – calories, types of food.
• Body weight significantly low (BMI < 18.5 in adults; children BMI percentile).
• Marked fear of weight gain or persistent behavior aimed at preventing it.
• Body image disturbance — “I feel fat” even when underweight.
• Subtypes:
  • Restrictive type — only food restriction.
  • Binge/purging type — vomiting, laxatives, exercise.
• Medical complications — bradycardia, hypotension, hypothermia, electrolyte imbalance, osteoporosis, amenorrhea, lanugo, cardiac arrhythmia, death.

6. Diagnosis

6.1 Unified diagnostic criteria

A. Significant low weight due to restricted food intake (BMI <18.5 in adults; below age-adjusted norm in children).

B. Intense fear of gaining weight or persistent behavior to avoid weight gain, even when weight is low.

C. Body image disturbance or lack of recognition of the seriousness of current body weight.

6.2 Source-specific clarifications

• DSM-5-TR — severity based on BMI (mild BMI ≥ 17, moderate 16–16.99, severe 15–15.99, extreme < 15).
• ICD-11 — a different severity scale: 6B80.0 significantly low body weight (adults BMI 18.5–14.0; children 5th–0.3rd percentile BMI-for-age), 6B80.1 dangerously low body weight (BMI < 14.0), 6B80.2 in recovery with normal body weight — the diagnosis is retained until full and lasting recovery. ICD-11 has no separate ‘atypical anorexia nervosa’ category (the term belongs to DSM-5-TR OSFED): a normal-BMI presentation is 6B80.2, or 6B8Y other specified feeding or eating disorders if the requirements are not met.
• NICE NG69 (Eating disorders, 2017, update) — diagnosis and treatment algorithms.

6.3 Diagnostic algorithm

1. Clinical interview.
2. EDE-Q (Eating Disorder Examination Questionnaire) or EDE — gold standard.
3. Medical examination — BMI, vital signs, electrolytes, EKG, bone densitometry.
4. Laboratory: complete blood count, electrolytes (especially K, P, Mg), liver, kidney, glucose, thyroid.
5. Comorbidity (MDD, OCD, anxiety).
6. Refeeding syndrome risk assessment (especially BMI <13 or minimal intake prolonged).

6.4 Differential diagnosis

7. Examination and assessment

• EDE-Q, EDE.
• Vital signs, BMI, weight history.
• Laboratory: complete blood count, electrolytes, liver, kidney, thyroid, FSH/LH, prolactin, vitamin D, B12, iron.
• EKG — bradycardia, QTc.
• DEXA — osteoporosis.
• C-SSRS suicide risk.

8. Treatment

8.1 General Principles (NICE NG69 · APA 2023)

1. Medical stabilization is critical: electrolytes, refeeding syndrome prophylaxis (phosphorus, magnesium, thiamine), cardiac monitoring.
2. Indication for hospitalization: BMI < 13, bradycardia < 40, hypokalemia, orthostatic changes, suicide risk, outpatient failure.
3. Psychotherapy first line:
   • FBT — Family-Based Treatment (Maudsley Model, Lock J., Le Grange D.) — gold standard in children and adolescents; 20 sessions in 3 phases.
   • CBT-E — Enhanced Cognitive Behavioral Therapy (Fairburn C.G.) — first-line in adults; 40 sessions over 20 weeks.
   • MANTRA, SSCM — alternatives for adults.
4. Pharmacotherapy — no specific effective drug for AN — antidepressant and antipsychotic for comorbidity; low-dose olanzapine (2.5–10 mg) may help weight gain in some patients (Attia E. et al. Am J Psychiatry 2019), but is not the primary intervention.
5. Nutrition — group or individual nutritionist; prophylaxis of refeeding syndrome — initial energy intake is low, phosphorus monitoring.
6. Duration of treatment is long (1–2 years or more).

8.2 Source-specific clarifications

• NICE NG69 (2017) — FBT in children and adolescents; CBT-E in adults.
• APA 2023 Practice Guideline for the Treatment of Patients with Eating Disorders, 4th ed.
• AED (Academy for Eating Disorders) — refeeding syndrome medical care standards.
• NICE — antidepressants not routinely recommended for AN.

Treatment methods

1. Family-Based Treatment / Maudsley Model (FBT) — Lock J., Le Grange D — 3-phase 20 sessions: (1) weight restoration – family controls food intake; (2) gradually returning control over eating to the adolescent; (3) adolescent-specific topics. Evidence: Lock J. et al. Arch Gen Psychiatry 2010 RCT.
2. Enhanced Cognitive Behavioral Therapy (CBT-E) — Fairburn C.G — Transdiagnostic (AN, BN, BED combined) approach; 40 sessions over 20 weeks; core focus on excessive value regarding body and weight. cbte.co.
3. Maudsley Anorexia Nervosa Treatment for Adults (MANTRA) — Schmidt U — Manualized for adults; focus on social-perfectionistic traits.
4. Specialist Supportive Clinical Management (SSCM) — Based on clinical supervision and psychoeducation.
5. Eating Disorder Examination Questionnaire (EDE-Q) — 28 items; baseline indicators and monitoring.
6. Refeeding Protocol (Maudsley, AED) — Initial 20 kcal/kg/day; phosphorus, magnesium, potassium supplements; thiamine; daily electrolyte monitoring.

9. Prognosis

• 50% remission, 30% residual symptoms, 20% chronic course.
• Mortality high (5–6%).
• Early intervention (especially FBT in adolescence) significantly improves prognosis.

10. Myths and misconceptions

Myth 1: “Anorexia is an ‘image’ disorder, not a serious medical condition”

Evidence: Arcelus 2011 meta-analysis — AN lifetime mortality 5–6%; highest among psychiatric disorders.

Myth 2: “The patient can eat voluntarily — just need to demand it”

Evidence: AN is a neurobiological and psychological complex disorder; the ‘volitional eating’ explanation is incorrect and harmful.

Myth 3: “Antidepressant is the main treatment for AN”

Evidence: NICE NG69 — antidepressants not routinely recommended for AN; may be used for comorbid MDD (more effective after weight restoration).

Myth 4: “AN only occurs in adolescent girls”

Evidence: AN also occurs in males (~10%); can develop in middle age; under-detection is common.

Myth 5: “The problem is resolved after weight restoration”

Evidence: Weight restoration is a crucial step, but without cognitive-behavioral intervention, relapse rates are high; psychotherapy is critical.

Myth 6: “Refeeding should be rapid”

Evidence: Rapid refeeding syndrome (hypophosphatemia, cardiac failure) possible; stepped approach and electrolyte monitoring critical.

Myth 7: The patient is perfectionistic and high-performing — this trait should be preserved

Evidence: Perfectionism is among the sustaining factors of AN; therapy is directed at this characteristic.

11. Sources

1. WHO. ICD-11. 6B80 Anorexia Nervosa. 2024.
2. APA. DSM-5-TR. 2022.
3. NICE NG69. Eating disorders: recognition and treatment. 2017, 2020 update.
4. APA. Practice Guideline for the Treatment of Patients With Eating Disorders, 4th ed. 2023.
5. Lock J., Le Grange D., Agras W.S. et al. Randomized clinical trial comparing family-based treatment with adolescent-focused individual therapy for adolescents with anorexia nervosa. Arch Gen Psychiatry 2010;67(10):1025–1032.
6. Fairburn C.G. Cognitive Behavior Therapy and Eating Disorders. Guilford Press; 2008.
7. Arcelus J., Mitchell A.J., Wales J., Nielsen S. Mortality rates in patients with anorexia nervosa and other eating disorders: a meta-analysis. Arch Gen Psychiatry 2011;68(7):724–731.
8. Attia E. et al. Olanzapine versus placebo in adult outpatients with anorexia nervosa. Am J Psychiatry 2019;176(6):449–456.
9. Smink F.R., van Hoeken D., Hoek H.W. Epidemiology of eating disorders. Curr Psychiatry Rep 2012;14(4):406–414.
10. Lock J., Le Grange D. Treatment Manual for Anorexia Nervosa: A Family-Based Approach. 2nd ed. New York: Guilford Press, 2013.
11. Schmidt U., Treasure J. Anorexia nervosa: valued and visible. A cognitive-interpersonal maintenance model. Br J Clin Psychol 2006;45(3):343–366.
12. Bulik C.M., Sullivan P.F., Tozzi F. et al. Prevalence, heritability, and prospective risk factors for anorexia nervosa. Arch Gen Psychiatry 2006;63(3):305–312.