Anterior cingulate pathology and social cognition in schizophrenia: a study of gray matter, white matter and sulcal morphometry

The anterior cingulate gyrus (ACG) is a critical structure for social cognitive processing; the pathology of this structure might be a major source of social dysfunction in schizophrenia. Multiple structural abnormalities of the ACG have been demonstrated in schizophrenia including changes in gray matter volume, white matter microstructures and macroscopic sulcal morphology. However, the interrelationships among these different abnormalities have not been investigated. Thus, the relationship between structural abnormalities in the ACG and social cognition in schizophrenia remains to be elucidated. Magnetic resonance imaging data were acquired at 3.0 T from 26 schizophrenic patients and 20 healthy participants. We performed anterior cingulate cortex (ACC) volumetry, evaluated diffusion tensor imaging of the anterior cingulum, analyzed paracingulate/cingulate sulcus (PCS/CS) morphology and investigated the interrelationships among these measures. We also investigated the association between ACG structural abnormalities and psychopathology, and the social cognition ability of schizophrenic patients as estimated by emotion attribution tasks. Compared with healthy subjects, schizophrenic patients exhibited reduced ACC volume, decreased fractional anisotropy in the anterior cingulum bilaterally and a poorly developed PCS/CS in the left hemisphere. No interrelationship was identified among these measures in the schizophrenic group. Schizophrenic patients performed poorly on emotion attribution tasks. Importantly, clinical symptoms and performance on emotion attribution subtasks were associated with ACC volumes and left PCS/CS variation in different ways. These results suggested that pathology of the ACC, anterior cingulum and PCS/CS is, at least partially, independent and has differential impacts on psychopathology and social cognitive impairment in schizophrenia.