Structural asymmetries in the Planum Temporale in patients with schizophrenia: A meta-analysis

Research on hemispheric asymmetries in schizophrenia, particularly in the planum temporale (PT), has yielded inconsistent findings. While some studies suggest a link between atypical PT asymmetries and schizophrenia, their conclusions are often limited by low statistical power or limited representativeness, while other studies fail to demonstrate this connection. This meta-analysis synthesizes literature on structural PT asymmetries in schizophrenia, employing robust meta-analytical methods. We compared PT size between patients with schizophrenia and unaffected controls. Following PRISMA guidelines, we conducted a systematic search process with the keywords (schizophrenia) OR (schizophrenic) OR (psychosis) AND (planum temporale) OR (asymmetries) OR (asymmetry) OR (laterality) on the databases PubMed, PubPsych, GoogleScholar, and ResearchGate. This search yielded 28 results with a total of n = 1409 participants (760 schizophrenia patients, 649 unaffected controls). Studies fulfilled the following inclusion criteria: reporting of primary MRI/CT data on PT asymmetry in schizophrenia and control groups; DSM/ICD-based schizophrenia diagnosis; sufficient PT size data for analysis and specification of measurement units, peer- reviewed and published in English, French, German, or Greek. Random effects meta- analyses revealed a significant atypical asymmetry and a significant size reduction of the left PT in patients with schizophrenia relative to controls. No significant effects were found for the right PT. Further analyses did not identify any significant moderating effects. Risk of Bias assessment revealed that most studies were of moderate to high quality with relatively low bias. The findings extend our understanding of the neurobiological underpinnings of schizophrenia.