Delusional Disorder
General Psychiatry Article Disclaimer
- DSM-5 criteria or ICD-11 diagnostic requirements are used to structure the Clinical Features and Diagnosis section. The classification system used is selected according to its clarity and suitability for non-specialist learning.
- The criteria are summarised and simplified rather than reproduced in full, while preserving their original diagnostic meaning.
- Where appropriate, a student-friendly pattern-recognition summary is provided to highlight the most clinically and exam-relevant features.
Exam tip (re-psychiatry questions)
- Do not attempt to memorise every DSM-5 or ICD-11 criterion word-for-word. However, it is important to read through the criteria and become familiar with the key symptom clusters, duration thresholds, exclusions, and distinguishing features highlighted in this article.
- Exam questions may not provide every feature required to meet the full diagnostic criteria. Familiarity with the criteria can help one recognise the most likely diagnosis, exclude important alternatives, and narrow the differential diagnosis.
Clinical Features and Diagnosis
High-yield pattern recognition for delusional disorder:
- Delusion(s) lasting for at least 1 month
- There should be NO prominent additional psychotic features (e.g. hallucination, disorganised speech / behaviour, -ve symptoms)
- Behaviour is not markedly bizarre or disorganised
- Relatively preserved functioning, apart from the direct consequences of the delusion
Classic exam pattern: A patient holds a persistent, firmly fixed belief (often persecutory, jealous, erotomanic, grandiose or somatic), but otherwise has relatively organised thinking, behaviour and day-to-day functioning.
As per the DSM-5 criteria, ALL the following must be met: [Ref]
| Diagnostic criteria | Description |
|---|---|
| Presence of symptoms | Presence of one or more delusions |
| Duration | At least 1 month |
| Functioning and behaviour | Apart from the direct effects and consequences of the delusion:
The delusion itself may still significantly affect a particular area of life (e.g. relationships, employment or interactions with the police) |
| Exclusion | Schizophrenia criteria NOT met
Mood episodes are NOT the predominant feature
The disturbance must not be:
|
Differential Diagnosis: Schizophrenia Spectrum and Related Disorders
Primary psychotic disorders: [Ref]
| Disorder | High-yield distinguishing features |
|---|---|
| Schizophrenia |
|
| Schizophreniform disorder |
|
| Schizoaffective disorder |
|
| Brief psychotic disorder |
|
| Delusional disorder |
|
Important mimics / differentials: [Ref1][Ref2]
| Disorder | High-yield distinguishing features |
|---|---|
| Substance / medication-induced psychotic disorder (drug-induced psychosis) |
|
| Psychotic disorder due to another medical condition (secondary / organic psychosis) | New psychosis (esp. prominent visual hallucinations) + neurological / systemic abnormalities or atypical presentation → consider secondary / organic psychosis
Key causes:
|
| Mania with psychotic features (bipolar disorder) |
|
| Schizotypal personality disorder |
|
| Schizoid personality disorder |
|
Management
Management should be individualised and usually undertaken with specialist input:
- Assess and manage risks to the patient or others
- Psychological interventions (individual CBT, family intervention) PLUS oral antipsychotics
- Treat associated conditions (e.g. depression, anxiety)
High-quality evidence specifically guiding the treatment of delusional disorder is limited [Ref]
See the Antipsychotic Pharmacology for more information on antipsychotics (including 1st generation vs 2nd generation, side effects, monitoring)