Cortical thickness alterations in afro-descendants with schizophrenia and bipolar disorder: An exploratory analysis

The impact of schizophrenia (SZ) and bipolar. disorder (BD) on brain structure is not fully understood, with most evidence derived from European, North American, and Asian populations. Our study aims to evaluate these morphometric changes in cortical thickness(CT) among Afro-descendants and indigenous people. We included neuroimaging data from 23 SZ patients, 20 BD patients, and 21 healthy controls (HC), aged between 22 and 31 years (mean age = 25 years). CT of 68 regions, as defined by the Desikan-Killiany atlas, was obtained using FreeSurfer. Statistical analysis involved analysis of covariance (ANCOVA) controlling for age, with Bonferroni correction for false discovery rate. BD patients showed significantly decreased CT in the right lateral orbitofrontal cortex and left pars orbitalis compared to SZ and HC. In a subset of clinical patients (SZ and BD), depressive symptoms, as measured by Diagnostic Interview for Psychosis and Affective Disorders(DIPAD) subscores, correlated negatively with left parahippocampal gyrus thickness, while manic symptoms correlated negatively with right lateral orbitofrontal CT. These findings underscore the importance of including underrepresented populations in neuroimaging research to better understand the structural brain alterations associated with psychiatric disorders.