Delusional Disorder

Definition | Aetiology | Pathophysiology | Risk factors | Signs and symptoms | Investigations | Management

Definition

Delusional disorder is a psychiatric condition characterised by the presence of persistent, non-bizarre delusions lasting at least one month, without significant impairment in overall functioning or marked hallucinations.

Aetiology

  • Biological factors:
    • Genetic predisposition (family history of schizophrenia or psychotic disorders).
    • Abnormal dopamine neurotransmission.
    • Structural brain abnormalities (e.g., frontal and temporal lobe dysfunction).
  • Psychosocial factors:
    • Social isolation.
    • Chronic stress or trauma.
    • Personality traits (e.g., paranoid or schizotypal personality disorder).
  • Medical conditions:
    • Neurodegenerative disorders.
    • Substance misuse (e.g., stimulant-induced psychosis).
    • Endocrine disorders (e.g., thyroid dysfunction).

Pathophysiology

  • Dysregulation of dopamine pathways, particularly the mesolimbic system.
  • Altered connectivity between the prefrontal cortex and limbic system, affecting reality testing.
  • Possible involvement of serotonin and glutamate dysregulation.

Risk factors

  • Family history of delusional disorder or psychosis.
  • Social isolation and lack of external reality testing.
  • Chronic stress or exposure to trauma.
  • Ageing (increased risk in older adults).
  • History of substance misuse.
  • Underlying medical or neurological conditions.

Signs and symptoms

  • Presence of one or more persistent delusions (non-bizarre in nature).
  • Minimal impact on daily functioning, apart from the delusion.
  • No significant hallucinations or disorganised thinking.
  • Types of delusions:
    • Persecutory: belief of being conspired against or harassed.
    • Grandiose: belief of having exceptional abilities or importance.
    • Jealous: belief that a partner is unfaithful.
    • Somatic: belief of having a medical condition or infestation.
    • Erotomanic: belief that another person is in love with them.
  • Possible agitation or irritability if the delusion is challenged.

Investigations

  • Clinical assessment: detailed psychiatric history and mental state examination.
  • Collateral history: from family or caregivers to assess functioning.
  • Blood tests: FBC, U&Es, LFTs, TFTs, vitamin B12, folate, glucose (rule out metabolic causes).
  • Urine drug screen: to exclude substance-induced delusions.
  • Neuroimaging (MRI/CT): if neurological pathology suspected.
  • Cognitive testing: if neurodegenerative disorder suspected.

Management

1. Psychological interventions:

  • Cognitive behavioural therapy (CBT) to address delusional beliefs.
  • Reality testing techniques.
  • Social skills training and reintegration.

2. Pharmacological management:

  • Atypical antipsychotics (e.g., risperidone, olanzapine, aripiprazole) for symptom control.
  • Typical antipsychotics (e.g., haloperidol) if atypicals are ineffective.
  • Anxiolytics or antidepressants if co-existing anxiety or depression.

3. Social and lifestyle interventions:

  • Encouraging social engagement and reality-based activities.
  • Family therapy for education and support.
  • Addressing substance misuse if relevant.

4. Referral:

  • Community mental health team (CMHT): for long-term support.
  • Psychiatrist: for medication initiation and monitoring.
  • Crisis team: if the patient poses a risk to self or others.
PsychiatrymypanotesDelusional Disorder