Write a short note on anorexia nervosa and bulimia nervosa.

Definition

Anorexia nervosa is an eating disorder characterised by restriction of energy intake leading to significantly low body weight, an intense fear of gaining weight, and disturbance in the way body weight or shape is experienced, with undue influence of weight on self-evaluation.

Bulimia nervosa is characterised by recurrent episodes of binge eating with a sense of loss of control, followed by recurrent inappropriate compensatory behaviour, occurring at least weekly for 3 months, with self-evaluation unduly influenced by body shape and weight. Body weight is typically normal or slightly raised, which is why bulimia is often concealed for years.

Both are far commoner in young women, with onset in adolescence or early adulthood. Anorexia nervosa has the highest mortality of any psychiatric disorder, from medical complications and from suicide.

Aetiology

Multifactorial — genetic predisposition; perfectionist, obsessional and anxious temperament; low self-esteem; family dynamics; childhood adversity or abuse; and sociocultural pressure, with higher rates in occupations emphasising thinness. Once established, starvation itself perpetuates the psychopathology through its effects on mood and cognition.

Clinical Features

Anorexia nervosa: marked weight loss, amenorrhoea (no longer a diagnostic requirement but common), cold intolerance, constipation, fatigue and dizziness. Examination shows bradycardia, hypotension, hypothermia, dry skin, lanugo hair, hair loss and, in prolonged cases, peripheral oedema. Patients frequently minimise symptoms and may be brought by family rather than presenting themselves.

Bulimia nervosa: often no abnormal physical signs. Where vomiting is repeated, look for dental enamel erosion, parotid swelling, and Russell's sign (calluses on the dorsum of the hand). Menstrual irregularity is common.

Medical Complications

Investigations

CBC, urea, electrolytes, magnesium and phosphate, calcium, glucose, LFT, thyroid function, ECG (QT interval), and DEXA scan for bone density in prolonged illness. There is no diagnostic test — investigations assess complications and risk.

Management

Management is multidisciplinary — physician, psychiatrist, dietitian and family — and should be delivered by a specialist service where available.

• Psychological therapy is the mainstay: CBT-ED (eating-disorder-focused cognitive behavioural therapy) is first-line in bulimia and in adults with anorexia; family-based therapy is first-line for adolescents with anorexia and has the best evidence in that group.
• Nutritional rehabilitation with supervised, gradual restoration of intake and weight, planned and monitored by a dietitian.
• Medication: fluoxetine has evidence in bulimia in reducing binge frequency, used with psychological therapy. No drug is effective for the core features of anorexia nervosa; antidepressants are used only for comorbid depression or OCD. Bupropion is contraindicated in eating disorders.
• Treat complications — correct electrolytes, manage osteoporosis, treat comorbid depression and anxiety.
• Indications for admission: very low or rapidly falling weight, bradycardia, hypotension, hypothermia, arrhythmia or prolonged QT, severe electrolyte disturbance, suicidal risk, or failure of outpatient management.

Prognosis

Roughly half recover fully, a third improve partially, and a fifth follow a chronic course. Outcome is better with early treatment, shorter duration of illness and adolescent onset. Long-term follow-up is required, as relapse is common.