Parietal lobe and thalamic nuclei volumetry in first-episode psychosis: Relation with trauma in a paired sibling study

Volumetric changes in the parietal lobe of patients with first-episode psychosis (FEP) remain underexplored, despite previous studies suggesting some structural abnormalities in this region. This cortical area, connected to the thalamus, is part of networks that have been linked to cognitive impairments in the schizophrenia spectrum. In this study, we processed structural MRI images using FreeSurfer to investigate the parietal cortex and thalamic nuclei in a cohort of 30 participants across three groups: 10 FEP patients, 10 unaffected siblings, and 10 matched healthy controls. We also examined whether traumatic experiences influenced volumetry in these regions. Notable differences were found in several parietal regions between patients and siblings compared to controls, with patients and siblings showing more similar volumetry. The left superior parietal gyrus exhibited a notable gradient of differences, suggesting a potential biomarker for distinguishing the groups. Significant volumetric differences were also observed in the anteroventral, medial geniculate, and ventral lateral thalamic nuclei. Additionally, a direct correlation was found between reduced gray matter volume in the left superior parietal gyrus and childhood trauma experience. These findings highlight the importance of studying parietal areas and considering genetic and environmental factors in future research.