Delusional disorder

ICD-10F22	Persistent delusional disorders
DSM-5-TRF22	Delusional Disorder

1. Definition and nosology

Delusional disorder (ICD-11: 6A24; DSM-5-TR: F22) — a psychotic disorder in which one or several delusions predominate for at least 3 months (ICD-11) or at least 1 month (DSM-5-TR), without meeting the full criteria for schizophrenia. The patient’s general behavior and functional level remain relatively intact except for the delusional state.

2. History

• Kraepelin (1899) — “paranoia” — systematized delusion without hallucinations.
• Esquirol J.E. (1810s) — the term “monomania”; Kahlbaum K. (1863) and Krafft-Ebing R. — the clinical description of paranoia.
• DSM-III-R (1987) — “Delusional Disorder” established as an official diagnosis; continuation of Kraepelin’s paranoia concept.
• ICD-11 (2019): Bizarre delusions are also permitted (in ICD-10 only non-bizarre); induced delusion (folie à deux) abolished as a separate category, incorporated into 6A24.

3. Epidemiology

• Lifetime prevalence: ~0.2% (Perälä 2007).
• Onset: middle age (35–55 years), significantly later than schizophrenia.
• Sex: approximately equal; differences in some subtypes (erotomania in women).
• Comorbidity: depression, anxiety, social isolation; high suicide risk.

4. Etiology and pathogenesis

• Genetic load is less than in schizophrenia; however, family history shows increased prevalence of paranoid personality and psychotic disorder.
• Sensory deprivation (hearing impairment) — increases risk of paranoid delusions in the elderly.
• Social isolation, migration, language barriers — risk factors.
• Neurobiological — dopaminergic dysregulation, but more localized than in schizophrenia; increased striatal dopamine synthesis in some studies (Howes O.D. reviews).

5. Clinical features

Subtypes (by delusional content)

• Persecutory: Most frequent — being followed by others, harm being planned.
• Jealousy (Othello syndrome): delusion about partner’s betrayal; high criminal risk.
• Erotomanic (Clérambault syndrome): belief that another person (usually of higher status) loves the patient.
• Grandiosity: special ability, talent, discovery, religious mission.
• Somatic: Belief in parasites in the body (Ekbom syndrome), emitting odor, deformity.
• Mixed and nonspecific.

Functional maintenance

Outside the delusion, the patient’s general behavior, affect, cognitive functions are relatively preserved; work and relationships can continue as long as they do not involve delusional content.

6. Diagnosis

6.1 Unified diagnostic criteria (DSM-5-TR · ICD-11)

A. One or more delusions persisting: ICD-11 — at least 3 months (usually much longer), DSM-5-TR — at least 1 month.

B. Criterion A for schizophrenia is not met (delusion is the sole or dominant symptom; hallucinations, if present, are minimal and related to the delusional content).

C. Functional preservation without a direct effect of the delusion; behavior not bizarre.

D. If an affective episode is present, it occurs during a small portion of the delusional period.

E. Exclusion of substance or organic cause.

6.2 Differences between sources

• ICD-11: Permission for bizarre delusions (also removed prohibition in DSM-5-TR); induced delusion (folie à deux) integrated into 6A24.
• DSM-5-TR: Subtype qualifiers (erotomanic, grandiose, jealous, persecutory, somatic, mixed, unspecified); ‘bizarre type’ additional qualifier.

6.3 Diagnostic algorithm

1. Clinical interview (general and especially delusional content).
2. Relative/friend interview — premorbid function, onset of delusions.
3. SCID-5 / MINI; PANSS / BPRS Positive Symptom Subscale.
4. Medical and neurological examination.
5. Toxicology screening; sensory (hearing, vision) test — mandatory in the elderly.
6. Brain MRI (at first episode).
7. Comorbid depression and suicide risk assessment.

6.4 Differential diagnosis

7. Examination and assessment

• PANSS / BPRS positive symptom subscale; structured documentation of concrete delusion content.
• Hearing and vision test (mandatory in the elderly).
• Laboratory: complete blood count, thyroid, B12, liver, glucose, toxicology screening, syphilis, HIV, ANA (lupus), ceruloplasmin (Wilson).
• Brain MRI — first episode, atypical clinical picture, elderly patient.
• Assessment of suicide and violence risk (C-SSRS, especially in jealousy delusions).

8. Treatment

1. Atypical antipsychotic at low dose (risperidone 1–3 mg, olanzapine 5–10 mg, aripiprazole 5–15 mg) — first-line. The evidence base is smaller than for schizophrenia; patient adherence is problematic (due to delusional content).
2. Pimozide was historically considered superior in erotomania and somatic delusions (Munro A. studies), but in modern practice it is used less often than the atypicals (QTc, EPS).
3. Psychotherapy — supportive therapy, building therapeutic alliance; CBT (non-confrontational work with delusional content, exploring alternative explanations).
4. Comorbid depression — SSRI.
5. Violence or suicide risk (especially delusions of jealousy) — hospitalization and involuntary treatment within the legal framework.
6. Sensory impairment — hearing devices or vision correction — can have a profound effect on paranoid delusions in older adults.
7. Social support — reduction of isolation; family psychoeducation.

8.1 Treatment methods

1. Non-confrontational CBT — Explore alternative explanations and evidence with the patient without openly denying the delusional content. Birchwood M., Trower P. studies — effective in schizophrenia and delusional disorder.
2. Supportive therapy and therapeutic alliance — Establish a long-term trusting relationship with the patient; strengthening of adherence.
3. PANSS positive symptom subscale — Standardized assessment of delusion severity and degree of interference.
4. Columbia-Suicide Severity Rating Scale (C-SSRS) — Suicide risk — particularly in jealousy and persecutory delusions, violence risk additionally assessed.

8.2 Differences between sources

• NICE CG178 — no separate algorithm for delusional disorder; general psychosis principles.
• APA 2021 — antipsychotic first-line; insight and adherence difficulty emphasized.
• Munro A. reviews (Cambridge Univ Press 1999) — subtype-specific clinical guidance.

9. Prognosis

• Prognosis is better than in schizophrenia — functional preservation, late onset.
• Adherence is the main limitation.
• Jealousy and somatic delusions relatively more difficult to treat.
• In older adults, improvement with sensory correction is possible.
• Monitoring — antipsychotic side effects, delusion severity, violence and suicide risk.

10. Myths and misconceptions

Myth 1: “The patient must be convinced of the falseness of their delusion”

Clinical logic: open confrontation disrupts therapeutic alliance and may reinforce delusions; the patient arrives at an explanation of his own: the doctor is against me too.

Evidence: Birchwood and Trower CBT approaches — a non-confrontational approach allowing the patient to explore alternative explanations themselves is effective.

Myth 2: “Delusional disorder can only be treated with psychotherapy, antipsychotics are unnecessary”

Evidence: An antipsychotic is the first-line pharmacotherapy; psychotherapy alone is insufficient. APA 2021, NICE CG178.

Myth 3: “Erotomania is only a female disorder, absent in males”

Evidence: Erotomania occurs in both sexes; higher risk of violence reported in male patients (Menzies R.P. et al. Br J Psychiatry 1995).

Myth 4: “Delusional jealousy is a sign of ‘great love’, not a medical condition”

Evidence: Othello syndrome is a clinical psychotic condition, high risk of violence and homicide against the partner; requires active medical intervention.

Myth 5: “Paranoid delusions in the elderly are ‘normal aging’”

Evidence: In older adults, paranoid delusions are often a marker for sensory deprivation (auditory impairment) or early dementia; they can be treatable. Hearing aids or vision correction sometimes yield significant improvement.

Myth 6: “Exorcism or religious intervention cures delusions”

Evidence: Psychotic symptoms are neurobiological; antipsychotic treatment is delayed.

Myth 7: “The delusional patient must be isolated — social contact is harmful”

Evidence: Social isolation, conversely, strengthens psychosis; social support and psychotherapy are recommended.

11. Sources

1. WHO. ICD-11. 6A24 Delusional disorder. 2024.
2. APA. DSM-5-TR. 2022.
3. NICE CG178. Psychosis and schizophrenia in adults. 2014/2019.
4. APA. Practice Guideline for Schizophrenia, 3rd ed. 2021.
5. Munro A. Delusional Disorder: Paranoia and Related Illnesses. Cambridge University Press; 1999.
6. Perälä J. et al. Lifetime prevalence of psychotic and bipolar I disorders in a general population. Arch Gen Psychiatry 2007;64(1):19–28.
7. Menzies R.P., Fedoroff J.P., Green C.M., Isaacson K. Prediction of dangerous behavior in male erotomania. Br J Psychiatry 1995;166(4):529–536.
8. Howes O.D., Kapur S. Schizophr Bull 2009;35(3):549–562.
9. Trower P., Birchwood M., Meaden A. et al. Cognitive therapy for command hallucinations: randomized controlled trial. Br J Psychiatry 2004;184:312–320.