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Substance-Induced Psychosis — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisSubstance-Induced PsychosisMRCPsych Paper B

A 22-year-old woman presents to the emergency department with her first episode of hallucinations and persecutory delusions. She reports frequent use of high-potency cannabis, and cannabis is considered likely to have precipitated the episode. Following medical assessment and observation, intoxication and delirium have been excluded, but her psychotic symptoms remain prominent and require active treatment. Which approach is most consistent with NICE guidance?

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Correct answer: B — Offer oral antipsychotic treatment while addressing cannabis misuse concurrently

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

B is correct. NICE advises reviewing diagnoses made during an emergency presentation, but substance misuse is not a reason to withhold appropriate treatment for sustained psychosis. Evidence-based treatment should be offered for both conditions, with antipsychotics used according to the NICE psychosis guideline and cannabis misuse addressed concurrently. For a first episode requiring active treatment, this includes offering an oral antipsychotic alongside appropriate psychological interventions. There is no required 2-week abstinence period, so A is incorrect. Benzodiazepines may sometimes help short-term agitation but are not sole treatment for sustained psychosis, excluding C. Psychological interventions alone are not the standard recommended offer, although a patient may choose them after informed discussion. Cannabidiol is not a NICE-recommended first-line antipsychotic treatment.

Reference: National Institute for Health and Care Excellence. CG120, Coexisting severe mental illness (psychosis) and substance misuse: assessment and management in healthcare settings, recommendations 1.4.16–1.4.25. 2011; presentational update 2024. https://www.nice.org.uk/guidance/cg120/chapter/Recommendations