Association of poor insight in schizophrenia with structure and function of cortical midline structures and frontopolar cortex.

Background: Poor insight is a central characteristic of psychosis and schizophrenia. Accumulating evidence indicates that cortical midline structures (CMS) and frontopolar cortex (FPC), both of which are associated with insight-related processing in healthy subjects, are among the most affected brain structures in schizophrenia. However, the hypothesis that direct associations between function of these brain regions and poor insight in schizophrenia exist has not been tested previously.

Methods: We studied 21 patients with schizophrenia and 17 healthy control subjects with structural and functional magnetic resonance imaging during a clinical insight task and a comparable control task. We assessed the level of insight, depression, positive and negative symptoms, and neurocognitive function, then adjusted correlation between insight and insight-task-related brain activation for potential confounders. Voxel-based morphometry was used to compare brain volumes between groups.

Results: Insight correlated strongly with the activation of the CMS and the FPC during the clinical insight tasks, independently of potential confounders. The CMS activation was stronger during the insight task than during the control task in patients. The functional correlates of insight matched the distribution of cortical volume reduction in the patient group.

Conclusions: These findings suggest a link between known regional brain abnormalities and the manifestation of poor insight in schizophrenia. The contribution of CMS to insight may be related to self-referential processing and that of FPC to the integration of multiple cognitive processes that are necessary for accurate evaluation of one's mental illness.