Neuropathological abnormalities in schizophrenia: evidence from magnetization transfer imaging

Post-mortem and structural brain imaging studies in schizophrenia have repo rted macroscopic changes such as global and regional cortical volume reduct ions, but it has been more difficult to characterize the histopathological changes that underlie these abnormalities. Magnetization transfer imaging ( MTI), a novel MRI technique, more sensitive to subtle or early neuropatholo gical changes than conventional MRI, provides a quantitative measure of mac romolecular structural integrity represented by the magnetization transfer ratio (MTR), In this study, we used MTI to examine 25 patients with schizop hrenia compared with 30 age-matched controls. A voxel-based analysis of the MTR maps revealed widespread MTR reductions in the cortex unrelated to vol ume reduction, predominantly in the frontal and temporal regions, in the sc hizophrenic patients when compared with controls. MTR reductions in bilater al parieto-occipital cortex and the genu of the corpus callosum were associ ated with the severity of negative symptoms in the schizophrenic patients, However, MTR changes were not related to other clinical variables of age, d uration of illness and current dose of antipsychotic medication. This study demonstrates that MTR abnormalities in the cortex can be detected in chron ic schizophrenia that may reflect subtle neuropathological changes involvin g neurones or neuronal processes, Longitudinal studies are needed to determ ine whether these abnormalities are related to disease progression or other disease manifestations such as cognitive changes.