Gross anatomical variations of the insular cortex in first-episode schizophrenia

Background: Magnetic resonance imaging (MRI) studies have revealed gray matter reductions in the insular cortex of schizophrenia patients. Despite large inter-individual anatomical variations in the insular gyri of human brains, the gross anatomical features of the insular cortex and their relationships with clinical characteristics remain largely unknown in schizophrenia. Methods: The present MRI study investigated variations in the insular gross anatomy (i.e., the development and split patterns of each gyrus and gyrus numbers) and their relationships with clinical variables and insular gray matter volumes in 66 patients with first-episode schizophrenia (FE-Sz) and 66 age- and sex-matched healthy controls. Results: The FE-Sz group had a significantly larger number of insular gyri bilaterally with well-developed accessory, middle short, and posterior long insular gyri than the control group, and this was associated with a younger onset age and severe positive symptoms. The split patterns of major insular gyri did not significantly differ between the groups. The FE-Sz group was also characterized by a smaller gray matter volume in the insular cortex than the control group; however, this was not associated with the insular gross anatomy or clinical characteristics. Conclusion: As the insular gyral organization reflects brain development during mid to late gestation, the gross anatomical features of the insular cortex in schizophrenia, which were independent of gray matter volumes, may be used as early neurodevelopmental abnormality markers for the illness.