Understanding Anorexia Nervosa: Symptoms, Causes, and Treatment

Anorexia nervosa, commonly referred to as anorexia, is an eating disorder characterized by low body weight, an intense fear of gaining weight, and a distorted body image. It is significantly more common in females than in males, being four to nine times more prevalent in females. Most cases present in adolescence, with 40% of diagnoses occurring between the ages of 15 and 19. While more common in Western countries, the incidence of anorexia is increasing in non-Western countries as well.

Prevalence and Demographics

Anorexia is most common in females, especially during adolescence. The risk of developing anorexia drops after age 21 and it is rarely diagnosed after age 40. Factors contributing to the development of anorexia include biological, psychological, genetic, and social influences. Heritability is estimated to be between 50% and 75%, and anxiety disorders often precede anorexia, which may be triggered by stressful life events.

Key Features and Symptoms

• Low Body Weight: Typically, a body mass index (BMI) below 18.5, or less than the fifth percentile in children and adolescents. Severe cases may involve a BMI less than 13 or 70% of the predicted BMI, posing an impending risk to life.
• Fear of Gaining Weight: Patients may believe they are overweight or that gaining weight would make them overweight, leading to behaviors aimed at preventing weight gain.
• Disturbed Body Image: Patients may express dissatisfaction with certain body parts and frequently measure body part sizes.

Physical and Psychological Manifestations

• Physical Signs: Include calluses on the dorsum of the hands (Russell’s sign) due to self-induced vomiting, dental erosion, parotid gland hypertrophy, dry skin, thin hair, lanugo (fine hair on the trunk, extremities, and face), and increased risk of osteoporosis.
• Psychological Traits: Patients often exhibit perfectionism and have histories of anxiety, depression, or obsessive-compulsive disorder (OCD). Menstrual irregularities are common, and 20% of deaths in anorexia are due to suicide.

Cardiovascular Complications

• Heart Issues: Include bradycardia, QT prolongation, atrioventricular (AV) blocks, and mitral valve prolapse due to reduced muscle and fat.
• Orthostatic Hypotension: May cause syncope due to bradycardia or hypovolemia.

Diagnosis

Diagnosis is clinical, based on DSM-5 criteria:

1. Restriction of Energy Intake: Leading to significantly low body weight in the context of age, sex, developmental trajectory, and physical health.
2. Intense Fear of Gaining Weight: Or persistent behavior that interferes with weight gain despite low body weight.
3. Disturbed Body Image: Undue influence of body weight or shape on self-evaluation, or persistent lack of recognition of the seriousness of current low body weight.

Subtypes of Anorexia

1. Restricting Subtype: No episodes of binge eating or purging in the preceding three months; weight loss achieved through dieting, fasting, or excessive exercise.
2. Binge Eating/Purging Subtype: Recurrent episodes of binge eating or purging in the preceding three months.

Differential Diagnosis

• Bulimia Nervosa: Key difference being that weight is usually normal or elevated in bulimia.

Lab Investigations

Lab tests may show normal results initially but can reveal abnormalities with increasing severity, such as leukopenia, hypokalemia, and thyroid function disturbances. Vital sign abnormalities include bradycardia, hypotension, and hypothermia.

Treatment

Goals: Correct urgent medical disturbances, regain weight, and normalize eating behavior.

Levels of Care:

• Inpatient: For severe malnutrition and declining treatment.
• Designated Eating Units: Structured programs for more intensive treatment.
• Outpatient: For less severe cases or following inpatient care.

Nutritional Rehabilitation:

• Caloric Intake: Increased through oral or nasogastric feeding.
• Weight Gain Goals: 1 to 2 kg per week as inpatients and 0.5 to 1 kg per week as outpatients.
• Thiamine Supplementation: Typically included to prevent deficiencies.
• Monitoring: Daily lab values to avoid refeeding syndrome, which involves electrolyte imbalances during nutritional reinstatement.

Psychotherapeutic Approaches:

• Cognitive Behavioral Therapy (CBT): Considered a first-line therapy.
• Maudsley Anorexia Nervosa Treatment for Adults (MANTRA): Tailored therapy for adults.
• Specialist Supportive Clinical Management (SSCM): Another therapeutic option.
• Family-Based Treatment (FBT): Effective for children and adolescents, involving parents in the refeeding process and transitioning responsibility to the child.

Pharmacological Therapy:

• Limited Efficacy: Generally not effective for core symptoms.
• Olanzapine: Sometimes used to aid weight gain, but does not address anxiety or weight obsession.
• Selective Serotonin Reuptake Inhibitors (SSRIs): Commonly prescribed but do not generally benefit eating behavior, weight, mood, or anxiety in anorexia patients, possibly due to malnourishment.