Neurological basis of poor insight in psychosis: A voxel-based MRI study

Background: As a reflection of poor insight, people with schizophrenia often disagree with carets and clinicians about whether (a) their experiences are abnormal, (b) they are mentally ill, and (c) they need treatment. Methods: This study used voxel-based morphometry to identify the associations between total and regional grey matter volumes and self-reported and observer-rated insight in 52 patients with schizophrenia or schizoaffective disorder. Thirty healthy participants were also studied. Results: There were positive associations in patients between (i) the ability to recognise experiences as abnormal and the total and right superior temporal gyrus grey matter volumes, (ii), awareness of problems ('something wrong') and the left precuncus grey matter volume and (iii) awareness of symptoms and attributing them to illness and grey matter volumes in the left superior-middle temporal gyrus and the right inferior temporal and lateral parietal gyri. The 'recognition of the need for medication' dimension did not correlate with total or any regional grey matter Volumes. Relative to controls, patients had less total and regional grey matter volumes in the thalamus and middle occipital and superior temporal gyri. Conclusions: Lower grey matter volumes in the temporal and parietal regions that have been implicated in self-monitoring, working memory and access to internal mental states are associated with poor insight on certain dimensions in psychosis. (C) 2008 Elsevier B.V. All rights reserved.