Reduced paralimbic system gray matter volume in schizophrenia: Correlations with clinical variables, symptomatology and cognitive function.

Background: Psychopathy is associated with dysfunction in regions that compose the paralimbic system, such as the orbitofrontal cortex (OFC), insular cortex (IC), temporal pole (TP), parahippocampal gyrus (PHG) and cingulate cortex (CC). However, findings of structural alterations in these regions are inconsistent in schizophrenia, and correlations between paralimbic system measures and symptomatology and cognitive function have not been investigated.

Method: 93 patients with schizophrenia and 99 healthy controls received structural magnetic resonance imaging and clinical and cognitive assessment. We compared gray matter volume (GMV) between the two groups using voxel-based morphometry, and evaluated correlations between abnormal GMVs and clinical variables, symptomatology and cognitive function. The assessment of cognition included measures of processing speed, verbal fluency and memory.

Results: Patients with schizophrenia demonstrated significant GMV decreases in the paralimbic system, including bilateral OFC, IC and TP (p < 0.05, FWE corrected). GMV decreases were also observed in bilateral superior temporal gyri (STG). The GMVs in bilateral OFC, left IC, left TP and bilateral STG were positively correlated with processing speed, and the GMVs in bilateral OFC were positively correlated with memory function in all participants. In our patient group, the GMV deficits were also associated with earlier age of onset, longer duration of illness, greater number of hospitalizations and more severe positive symptoms.

Conclusions: GMVs in the paralimbic system were significantly reduced in schizophrenia, and these abnormalities were correlated with clinical variables, symptomatology and cognitive function. These results suggest the paralimbic system plays an important role in the pathophysiology of schizophrenia.