Lewy Body Dementia — MRCPsych Paper B MCQ

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ModerateOld Age PsychiatryLewy Body DementiaMRCPsych Paper B

An 80-year-old man with dementia with Lewy bodies has recurrent visual hallucinations that cause severe distress. Reversible causes have been excluded and psychosocial and environmental interventions have been unsuccessful. If antipsychotic treatment is being considered, which option is formally contraindicated in dementia with Lewy bodies according to its UK Summary of Product Characteristics?

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Correct answer: B — Haloperidol

Haloperidol is correct because its UK SmPC lists dementia with Lewy bodies as a contraindication. DLB is associated with marked antipsychotic sensitivity: dopamine blockade may abruptly worsen rigidity and bradykinesia and can precipitate reduced consciousness or neuroleptic malignant syndrome. Olanzapine is the key distractor because NICE advises against it for hallucinations and delusions in Parkinson's disease; this made the original broadly worded question potentially ambiguous. The repaired stem asks specifically about the formal UK SmPC contraindication, making haloperidol unique. Quetiapine and clozapine have lower motor liability but remain potentially hazardous; clozapine also requires specialist blood monitoring. Aripiprazole may aggravate parkinsonism and is not a preferred treatment for psychosis in DLB.

Reference: Electronic Medicines Compendium, Haloperidol 5 mg/ml solution for injection, Summary of Product Characteristics, section 4.3 Contraindications, updated 30 June 2025: https://www.medicines.org.uk/emc/product/100592/smpc