[Connectivity analyses of white matters in schizophrenia]

Investigation of brain morphology in schizophrenia has improved by the advance of magnetic resonance imaging (MRI). Recently, pathology of white matter has been extensively investigated from the viewpoint of disconnection hypotheses of schizophrenia. Diffusion tensor imaging (DTI) technique enables us to evaluate the integrity of white matter tracts, using indices including fractional anisotropy (FA). The authors revealed that the integrity of white matter is decreased in widespread regions, compared with healthy controls. The mean FA value of the whole white matter skeleton was significantly lower and correlated with global mean cortical thicknesses in schizophrenia. And in the regional level, the mean FA value of the right thalamo-orbitofrontal pathway was significantly lower and correlated with the thicknesses of the right frontal polar and lateral orbitofrontal cortices in schizophrenia. The corresponding correlation was not found in healthy subjects. These findings, corroborating recent molecular genetic and post-mortem findings, suggest the intertwined nature of gray and white matter pathology of schizophrenia.