Mesocortical Pathway — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisMesocortical PathwayMRCPsych Paper B

A 24-year-old man with schizophrenia has persistent avolition, reduced spontaneous speech and blunted affect after his positive and depressive symptoms have resolved. He has no sedation or extrapyramidal adverse effects. According to the classical dopamine hypothesis of schizophrenia, reduced dopaminergic activity in which pathway is most closely associated with these primary negative symptoms?

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Correct answer: E — Mesocortical pathway

The answer is E, the mesocortical pathway. In the classical dopamine hypothesis, reduced dopaminergic transmission from the ventral tegmental area to the prefrontal cortex is associated with primary negative symptoms and cognitive impairment. The stem excludes important secondary negative symptoms caused by depression, persisting psychosis, sedation or extrapyramidal effects. Mesolimbic dopamine hyperactivity is classically associated with positive symptoms. The nigrostriatal pathway regulates movement, and its D2 blockade causes extrapyramidal adverse effects. Tuberoinfundibular dopamine normally inhibits prolactin secretion, so blockade can cause hyperprolactinaemia. The mesohabenular pathway is not the classical explanation for negative symptoms. This pathway model is a useful examination framework but is an oversimplified hypothesis; negative symptoms are heterogeneous, and direct evidence for cortical hypodopaminergia remains incomplete.

Reference: Collo G, Mucci A, Giordano GM, Merlo Pich E, Galderisi S. Negative Symptoms of Schizophrenia and Dopaminergic Transmission: Translational Models and Perspectives Opened by iPSC Techniques. Frontiers in Neuroscience, 2020. https://pubmed.ncbi.nlm.nih.gov/32625059/