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Delusional Disorder Features — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisDelusional Disorder FeaturesMRCPsych Paper B

A 48-year-old has believed for 8 months that neighbours are contaminating his garden. His beliefs are fixed and have led to repeated complaints, but he continues to work and manage his self-care. There are no persistent hallucinations, formal thought disorder, passivity phenomena or negative symptoms. There is no significant mood episode, substance use or medical cause. Which feature most strongly supports delusional disorder rather than schizophrenia?

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Correct answer: B — Persistent delusions predominate without the broader schizophrenia syndrome or pervasive functional decline

Explanation lettering: C = shown as A · A = shown as C

B is correct. Delusional disorder is distinguished by persistent, predominant delusions without the broader syndrome required for schizophrenia. Hallucinations, if present, are not prominent, and formal thought disorder, passivity phenomena and negative symptoms are absent. Functioning may be impaired by actions arising from the delusion, but deterioration is not usually pervasive outside that context. Early onset with progressive functional decline would favour schizophrenia (A). Delusional disorder is not restricted to people older than 65 (C) or to persecutory themes; erotomanic, grandiose, jealous and somatic themes can occur (D). A direct relationship to intoxication or withdrawal would instead suggest a substance-induced psychotic disorder (E).

Reference: Rossi Grauenfels D, Henriksen MG, Nordgaard J. Delusional disorder and its differentiation from schizophrenia: A narrative review. 2026. https://pubmed.ncbi.nlm.nih.gov/42138058/