[Progress in MRI studies of the schizophrenia spectrum]

Morphologic brain imaging studies using magnetic resonance imaging (MRI) have demonstrated gray matter reduction in the frontal and temporolimbic-paralimbic regions in schizophrenia. Although the causes as well as timing and course of these morphologic changes remain elusive, these changes might at least partly reflect early neurodevelopmental abnormalities. On the other hand, longitudinal MRI studies suggest that patients with schizophrenia and other psychoses also show progressive brain morphologic changes during the transition period as well as initial period after the onset of florid psychosis. Recently, increasing evidence based on MRI findings in individuals at risk of developing psychosis (at-risk mental state: ARMS) suggests that ARMS subjects who subsequently develop psychosis show baseline brain changes, which could be at least partly predictive of later transition. In this article, we review recent findings in ARMS and our own neuroimaging findings regarding the schizophrenia spectrum. We also refer to remaining issues to be addressed before applying these neuroimaging research findings in a clinical setting.