Delusional disorder

• Erotomanic (De Clerambault syndrome):

  • Patients present with the belief that some important person is secretly in love with them
  • May lead to inappropriate harassment of the individual by the patient
  • Patient is most often a young, single woman
  • Frequently occurs without other psychiatric or neurological disease
• Grandiose:

  • Patients believe they fill some special role, have some special relationship, or possess some special ability
  • May be involved with social or religious organizations
• Jealous (Othello syndrome):

  • Patient possess the fixed belief that their spouse or partner has been unfaithful
  • Often patients try to collect evidence and/or attempt to restrict their partner's activities
  • May be associated with forensic cases involving murder
• Persecutory:

  • Believe they are being plotted against, spied on, maligned, or harassed
  • May repeatedly file lawsuits or reports to the police
  • Sometimes resort to violence in retaliation for imagined persecution
• Somatic:

  • Preoccupied with a bodily function or attribute, such as imagined physical deformity
  • Varying presentation - from those who have repeat contact with doctors requesting various forms of medical or surgical treatment to patients who are delusionally concerns with bodily infestation (e.g. parasites), deformity or odour
• Mixed:

  • Presence of 2+ themes - no single theme predominating
• Nihilistic:

  • Delusional belief of being dead, decomposed, having lost one's own internal organs or even existing entirely as a human being
  • Also called Cotard's syndrome or walking corpse syndrome
• Capgras syndrome:

  • Delusion that an identical duplicate has replaced someone close to them
  • May be their spouse, family member or close friend
  • Person may be suspicious and aggressive towards the imposter
• Symptoms must be present for at least 1 month

  ICD-11 states 3 months but if less than this, allow diagnosis under 'delusional disorder unspecified'
• Overview:

  • Characterised by the development of a delusional or set of related delusions, persisting for at least 1 month
  • Absence of depressive, manic or mixed mood episodes
  • Other characteristic symptoms of schizophrenia are not present
  • Not a manifestation of another mental or medical condition, or due to the effect of a substance or medication
• Differential diagnosis:

  • Substance-induced delusional disorders e.g. alcohol, cannabis
  • Medications - steroids, antibiotics, dopamine agonists, anticholinergics
  • Physical disorders - brain tumour, head injury, CNS infection, epilepsy, neurodegenerative disorders, endocrine disorders, vitamin deficiencies
  • Mood disorders with delusions
  • Schizophrenia
  • Delirium
  • Dementia
  • Paranoid personality disorder
  • Significant overlap with - body dysmorphic disorder, OCD
• Risk factors:

  • Marked distrust and suspicion
  • Social isolation
  • Heightened feelings of jealousy
  • Fragile self-esteem
  • A tendency to see their own defects in others
  • Rumination over the meaning of events and motivation of others
• Management:

  • Difficult to treat
  • A good doctor-patient relationship is key
  • Psychotherapy
  • Separation from the source or focus of delusional idea
  • Antipsychotics - limited evidence but best results when psychotherapy is combined with antipsychotics