Do Subjects at Clinical High Risk for Psychosis Differ from those with a Genetic High Risk? – A Systematic Review of Structural and Functional Brain Abnormalities
BACKGROUND Volumetric MRI abnormalities similar to those evident in schizophrenia are also evident in people at very high risk of psychosis. Which volumetric abnormalities are related to psychotic illness, as opposed to vulnerability to psychosis is unclear. The aim of the study was to compare regional gray matter volume in people before and after the onset of psychosis using a within-subject prospective design. METHODS MRI data were acquired from individuals when they presented with an at-risk mental state (ARMS, n=20). Over the following 3 years, 10 subjects developed psychosis and 10 did not. Subjects were re-scanned after the onset of psychosis or at the end of follow-up if they did not become psychotic. Images were processed and analyzed using voxel-based morphometry (SPM5). RESULTS In subjects who developed psychosis there were longitudinal volume reductions in the orbitofrontal, superior frontal, inferior temporal, medial and superior parietal cortex, and in the cerebellum. There were no longitudinal changes in subjects who did not develop psychosis. CONCLUSIONS The onset of psychosis was associated with a reduction in gray matter volume in frontal, temporal and parietal cortex. These abnormalities may be particularly associated with psychotic illness, as opposed to a vulnerability to psychosis.