PD Psychosis — RACP Adult Medicine MCQ

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

ModerateNeurologyPD PsychosisRACP Adult Medicine

A 65-year-old man with Parkinson's disease on levodopa/carbidopa develops visual hallucinations (seeing small animals) and paranoid ideation. His MMSE is 24/30. Which medication should be tried first to manage his psychotic symptoms?

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

Reveal the answer and explanation

Correct answer: E — Quetiapine 12.5–25 mg nocte

In Parkinson's disease psychosis, standard antipsychotics (haloperidol, olanzapine, risperidone) worsen parkinsonism dramatically due to D2 receptor blockade. Quetiapine (at very low doses, 12.5–25 mg nocte) is tried first due to its relatively low D2 affinity. If quetiapine is ineffective, clozapine (the only antipsychotic with level 1 evidence for PD psychosis – low D2 affinity) is used, though it requires regular blood monitoring. Pimavanserin (a selective 5-HT2A inverse agonist without D2 activity) is approved overseas but not yet PBS-listed in Australia.

Reference: eTG – 2025 – Neurology; MDS – 2023 – PD Psychosis Management