Structural asymmetries in the planum temporale in patients with schizophrenia: A meta-analysis

Research on planum temporale (PT) asymmetries in schizophrenia has yielded inconsistent findings: Some studies suggest a link between atypical PT asymmetries and schizophrenia, their conclusions are often limited by low statistical power or limited representativeness, while others find no association. The PT, a region crucial for auditory and language processing, seems particularly relevant in schizophrenia because of the disorder's symptomatology regarding changes in language processing. This meta-analysis synthesizes literature on structural PT asymmetries in schizophrenia compared to controls, employing robust meta-analytical methods. Following PRISMA guidelines, we conducted a systematic search process in 2024 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 inclusion criteria: reporting of primary MRI/CT data on PT asymmetry in schizophrenia and controls; DSM/ICD 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. Further analyses did not identify any significant moderating effects. Risk of Bias assessment (following the Newcastle-Ottawa scale) 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.