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Negative Symptoms and Prolactin — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisNegative Symptoms and ProlactinMRCPsych Paper B

A 26-year-old man with schizophrenia has been free of positive symptoms for 12 months while receiving risperidone LAI 50 mg every 2 weeks. Since the dose was increased, he has developed marked avolition and reduced spontaneity with mild bradykinesia. Assessment finds no depressive episode or substance misuse, and repeat testing shows markedly elevated prolactin. Following shared decision-making, he wishes to change antipsychotic but remain on an LAI. Which strategy best addresses both the likely secondary negative symptoms and the hyperprolactinaemia?

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Correct answer: A — Cross-titrate to oral aripiprazole, then use aripiprazole LAI

Explanation lettering: B = shown as A · A = shown as B · E = shown as C · C = shown as D · D = shown as E

B is correct. The temporal relationship to risperidone dose escalation, mild bradykinesia, absence of positive symptoms and exclusion of depression suggest that at least some of the apparent negative symptoms are secondary to dopamine blockade. Risperidone also commonly raises prolactin. Switching to aripiprazole removes the prolactin-raising drug and introduces a prolactin-sparing partial dopamine agonist; clinical evidence supports reductions in prolactin, motor adverse effects and negative-symptom scores. Oral tolerability and stabilisation should be established before aripiprazole LAI. Increasing risperidone is unlicensed above 50 mg every 2 weeks, produced no additional benefit in trials and may worsen both problems. Procyclidine may reduce parkinsonism but does not correct hyperprolactinaemia and adds anticholinergic burden. Fluoxetine is not indicated without depression and can increase risperidone exposure through CYP2D6 inhibition. Lithium addresses neither problem.

Reference: Lee BJ et al. Effect of aripiprazole on cognitive function and hyperprolactinemia in patients with schizophrenia treated with risperidone. Clinical Psychopharmacology and Neuroscience. 2013;11(2):60–66. https://www.medicines.org.uk/emc/product/6869/smpc