Cortical surface characteristics among offspring of schizophrenia subjects

A systematic study of cortical surface parameters in adolescent offspring of schizophrenia subjects before clinical manifestation could clarify neurodevelopmental antecedents of increased genetic risk. We examined these measures obtained on structural magnetic resonance imaging (MRI) scans at baseline and one year on a series of offspring of schizophrenia parents and healthy subjects.

We measured cortical surface area, curvature and thickness using BRAINS2 on structural MRI scans acquired using 1.5 T GE whole body scanner on all subjects. We examined the differences between study groups at baseline using mixed-effects models, and longitudinal trajectory of these measures using linear mixed-effects models.

At baseline, offspring of schizophrenia parents showed reduced gyral surface area in the fronto-parietal lobes along with increased sulcal curvature and parietal gyral cortical thinning compared to healthy subjects. Prospective follow up of these subjects for one year showed shrinking of the total surface area, especially in the bilateral frontal and occipital regions along with preservation of cortical thickness among offspring of schizophrenia parents whereas healthy subjects showed preserved or increased surface area and cortical thinning. Correlation of these measures with lobar volumes was not observed at baseline cross-sectional comparisons but was observed in longitudinal examinations.

Our observations suggest that adolescents with genetically elevated risk for schizophrenia show altered cortical surface measures affecting cortical surface area and thickness differentially suggesting a divergent trajectory of neurodevelopment. Cortical surface measures appear to be more sensitive to genetic liability to schizophrenia compared to volumetric measures.