DDx

• Medications with an anticholinergic effect, particularly:

  • Anticholinergic urological drugs (e.g., oxybutynin, solifenacin and tolterodine)
  • Antihistamines (e.g., chlorphenamine and promethazine)
  • Tricyclic antidepressants (e.g., amitriptyline)

   
• Psychiatric conditions include:

  • Depression
  • Psychosis
  • Delirium (e.g., secondary to infection)
• Neurological conditions include:

  • Brain tumours (particularly affecting the frontal lobes)
  • Parkinson’s disease
  • Huntington’s disease
  • Progressive supranuclear palsy
• Endocrine conditions include:

  • Hypothyroidism
  • Adrenal insufficiency
  • Cushing’s syndrome
  • Hyperparathyroidism (causing hypercalcaemia)
• Nutritional deficiencies include:

  • Vitamin B12 deficiency
  • Thiamine deficiency (causing Wernicke-Korsakoff syndrome)