Anorexia Nervosa

Definition | Aetiology | Risk Factors | Clinical Presentation | Investigations | Management | When to Refer | References

Definition

Anorexia Nervosa is a serious mental health disorder characterised by an intense fear of gaining weight, a distorted body image, and an extreme restriction of food intake, leading to significantly low body weight. It is associated with severe physical and psychological complications and has the highest mortality rate of any psychiatric disorder.

Aetiology

The exact cause of anorexia nervosa is not fully understood, but it is believed to result from a combination of genetic, biological, psychological, and environmental factors:

• Genetic Factors: Family history of eating disorders or other mental health conditions may increase the risk, suggesting a genetic predisposition.
• Biological Factors: Neurobiological abnormalities, including imbalances in neurotransmitters such as serotonin and dopamine, may contribute to the development of anorexia.
• Psychological Factors: Perfectionism, obsessive-compulsive traits, and low self-esteem are common psychological factors associated with anorexia nervosa.
• Environmental Factors: Societal pressures, cultural ideals of thinness, and exposure to dieting or weight-related teasing during childhood or adolescence can contribute to the development of anorexia.
• Trauma: A history of trauma, such as abuse or significant loss, may also play a role in the onset of anorexia nervosa.

Risk Factors

Several factors increase the likelihood of developing anorexia nervosa:

• Gender: Females are more commonly affected than males, although the incidence in males is increasing.
• Age: Anorexia nervosa typically begins during adolescence or early adulthood, though it can occur at any age.
• Family History: Having a close relative with an eating disorder or another mental health condition increases the risk.
• Personality Traits: Traits such as perfectionism, high levels of self-discipline, and obsessive-compulsive tendencies are often seen in individuals with anorexia.
• Dieting and Weight Loss: Engaging in dieting or excessive exercise, particularly during adolescence, can increase the risk of developing anorexia.
• Societal Pressures: Exposure to cultural ideals of thinness and the promotion of unrealistic body standards in the media.

Clinical Presentation

Anorexia nervosa presents with a range of psychological, behavioural, and physical symptoms:

Psychological and Behavioural Symptoms

• Intense Fear of Gaining Weight: Despite being underweight, individuals with anorexia have an overwhelming fear of gaining weight or becoming fat.
• Distorted Body Image: A perception of being overweight, even when severely underweight. Individuals may focus on specific body parts they believe are "too fat."
• Severe Food Restriction: Extreme limitation of food intake, often coupled with calorie counting, avoiding certain foods, or skipping meals.
• Excessive Exercise: Engaging in compulsive physical activity to burn calories, even when it poses a health risk.
• Preoccupation with Food: An obsessive focus on food, dieting, and body weight, including preparing elaborate meals for others without eating themselves.
• Social Withdrawal: Avoidance of social situations, particularly those involving food, due to fear of eating or being judged.

Physical Symptoms

• Significantly Low Body Weight: Weight loss leading to a body mass index (BMI) that is significantly below the normal range for age and height.
• Amenorrhoea: The absence of menstruation in women and girls who have reached puberty.
• Bradycardia and Hypotension: Slow heart rate and low blood pressure, which can lead to fainting or dizziness.
• Lanugo: The development of fine, downy hair on the face and body as a response to low body fat and cold intolerance.
• Gastrointestinal Issues: Constipation, abdominal pain, and bloating due to restricted food intake.
• Osteoporosis: Loss of bone density due to malnutrition, increasing the risk of fractures.
• Electrolyte Imbalances: Low levels of potassium, sodium, and other essential electrolytes, which can lead to life-threatening complications such as cardiac arrhythmias.

Investigations

The diagnosis of anorexia nervosa is primarily clinical, based on a detailed history and physical examination. Additional investigations are often required to assess the physical complications of the disorder:

• Body Mass Index (BMI): Calculation of BMI to assess the degree of underweight and monitor progress during treatment.
• Blood Tests: Full blood count (FBC), electrolytes, liver function tests (LFTs), renal function tests, and thyroid function tests to assess for malnutrition-related complications.
• Electrocardiogram (ECG): To detect bradycardia, arrhythmias, or other cardiac abnormalities associated with anorexia nervosa.
• Bone Density Scan (DEXA): To assess for osteoporosis or low bone density in individuals with prolonged malnutrition or amenorrhoea.
• Psychiatric Assessment: A comprehensive mental health evaluation to assess for co-occurring mental health conditions such as depression, anxiety, or obsessive-compulsive disorder (OCD).
• Nutritional Assessment: Evaluation of dietary intake and nutritional status by a dietitian to guide nutritional rehabilitation.

Management

The management of anorexia nervosa requires a multidisciplinary approach involving medical, nutritional, and psychological interventions:

Medical Management

• Weight Restoration: Gradual refeeding to restore weight and correct nutritional deficiencies, often under the supervision of a medical team. In severe cases, hospitalisation may be required.
• Monitoring and Management of Medical Complications: Regular monitoring of vital signs, electrolytes, and cardiac function to manage complications such as bradycardia, hypotension, and electrolyte imbalances.
• Pharmacotherapy: While no medications are specifically approved for anorexia nervosa, antidepressants such as SSRIs may be used to treat co-occurring depression or anxiety. Olanzapine may be considered to help with weight gain and reduce obsessive thoughts about food.

Psychological Therapies

• Cognitive Behavioural Therapy (CBT): Focuses on changing distorted beliefs about body image, weight, and food, and developing healthier eating behaviours.
• Family-Based Therapy (FBT): Particularly effective for adolescents, FBT involves the family in supporting the individual’s recovery, including managing meals and addressing family dynamics.
• Interpersonal Therapy (IPT): Addresses interpersonal issues that may contribute to the development or maintenance of anorexia nervosa.
• Dialectical Behaviour Therapy (DBT): May be used to help individuals with emotional regulation and reduce self-harming behaviours.

Nutritional Rehabilitation

• Dietitian Involvement: A registered dietitian can provide a structured meal plan, education on balanced nutrition, and support for normalising eating patterns.
• Monitoring Nutritional Intake: Close monitoring of food intake, weight gain, and physical health to ensure progress and prevent refeeding syndrome.
• Addressing Malnutrition: Gradual reintroduction of a balanced diet to correct nutritional deficiencies and promote healthy weight gain.

When to Refer

Referral to a specialist eating disorder service or inpatient treatment may be necessary in the following situations:

• Severe malnutrition or rapid weight loss that poses a risk to life or health.
• Medical complications such as electrolyte imbalances, bradycardia, or organ dysfunction requiring hospitalisation.
• Failure to respond to outpatient treatment or worsening of symptoms despite intervention.
• Presence of co-occurring mental health conditions such as severe depression, anxiety, or suicidality that require intensive treatment.
• Need for specialised psychological therapies, such as FBT or DBT, that are not available in primary care settings.

References

1. NHS (2024) Anorexia Nervosa. Available at: https://www.nhs.uk/conditions/anorexia/ (Accessed: 26 August 2024).
2. National Institute for Health and Care Excellence (2024) Eating Disorders: Recognition and Treatment. Available at: https://www.nice.org.uk/guidance/ng69 (Accessed: 26 August 2024).
3. British Medical Journal (2024) Anorexia Nervosa: Clinical Review. Available at: https://www.bmj.com/content/350/bmj.h368 (Accessed: 26 August 2024).

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