Prefrontal gyrification in psychotic bipolar I disorder vs. schizophrenia.

Bipolar disorder and schizophrenia share phenotypic and genotypic features, but might differ in aspects of abnormal neurodevelopmental trajectories. We studied gyrification, a marker of early developmental pathology, in high-resolution MRI scans of 34 patients with schizophrenia, 17 euthymic bipolar I disorder patients with previous psychotic symptoms, and 34 matched healthy controls in order to test the hypothesis of overlapping and diverging prefrontal gyrification abnormalities. We applied a novel, validated method for measuring local gyrification in each vertex point of the reconstructed cortical surface. Psychotic bipolar I patients had higher gyrification in dorsal anterior and infragenual cingulate cortex compared to either schizophrenia or healthy controls, while schizophrenia patients had higher gyrification than controls in anterior medial (BA 10) and orbitofrontal areas, altogether indicating disease-specific alterations in the prefrontal cortex. Our findings indicate gyrification changes in a specific subgroup of bipolar I disorder to affect an area relevant to emotion regulation, and distinct from changes seen in schizophrenia.