Antipsychotics in DLB — MRCPsych Paper B MCQ

Instant feedback + full explanation. One question, done properly.

ModerateOld Age PsychiatryAntipsychotics in DLBMRCPsych Paper B

A 68-year-old man with dementia with Lewy bodies has recurrent visual hallucinations causing severe distress. Delirium, pain, medication-related causes and environmental triggers have been excluded or addressed. Psychosocial interventions and an optimised trial of a cholinesterase inhibitor have not adequately controlled the hallucinations. After discussing off-label use and the risk of severe antipsychotic sensitivity reactions, the consultant decides a cautious antipsychotic trial is necessary. Which antipsychotic is the most appropriate to initiate at the lowest possible dose?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Quetiapine

E. Quetiapine is the single best option. NICE NG97 restricts antipsychotics in dementia to agitation, hallucinations or delusions causing severe distress or risk of harm, and warns that in DLB they can worsen motor features and precipitate severe antipsychotic sensitivity reactions; cholinesterase inhibitors are first-line for psychotic symptoms in DLB. When an antipsychotic is unavoidable, UK guidance (e.g., NHS Scotland Right Decisions, reflecting the DLB Consortium reports) identifies low-dose quetiapine as relatively safer, reflecting its low D2 occupancy and low extrapyramidal liability; use is off-label, so consent, the lowest effective dose and early review are essential. Haloperidol, a potent first-generation D2 antagonist, must be avoided and is contraindicated in DLB in UK SmPCs. Chlorpromazine combines significant dopamine blockade with anticholinergic and hypotensive effects that worsen cognition and falls. Risperidone has dose-dependent extrapyramidal effects and its UK licence in dementia is limited to Alzheimer's disease. Aripiprazole can cause akathisia and parkinsonism and is not the preferred UK choice in DLB.

Reference: NHS Scotland Right Decisions (NHSGGC MyPsych Medicines Companion), 'Prescribing in dementia' – antipsychotics in Lewy body disease: https://www.rightdecisions.scot.nhs.uk/mypsych-app/working-in-greater-glasgow-clyde/medicines-companion/antipsychotics/prescribing-in-dementia/ ; NICE NG97 Dementia: assessment, management and support (2018): https://www.nice.org.uk/guidance/ng97/chapter/Recommendations