Cortical Thickness and Connectivity in Schizophrenia

It is salutary to recall that schizophrenia was generally regarded as a functional psychosis, rather than an organic psychosis like dementia, at that time, about 30 years ago. One implication of this diagnostic dogma was that the brain was not expected to look structurally (organically) abnormal in schizophrenia. The first CT studies generated intense controversy by providing disruptive evidence for significant enlargement of the ventricles It is a measure of the theoretical impact of neuroimaging in psychiatry that the prior concept of functional psychosis has been largely abandoned in the face of overwhelming evidence of structural brain imaging abnormalities in schizophrenia. It is now beyond reasonable doubt that the brain does not look structurally normal in schizophrenia, but it remains an open question how best to characterize and interpret the abnormalities disclosed by contemporary MRI research Advances in statistical theory and computational processes have made it routine to estimate any regional MRI parameter, like cortical thickness, at hundreds of well-defined cortical areas and subcortical nuclei. Whole-brain maps of MRI abnormalities associated with schizophrenia have been published in a standard anatomical format and can be quantitatively meta-analyzed . It is clear that there are anatomically widespread or spatially distributed abnormalities in macrostructural MRI markers, like volume and thickness, measured over multiple voxels representing each region. There is also increasing evidence that microstructural MRI markers, like magnetization transfer ratio, can provide diagnostically relevant information about the tissue composition of each voxel, allowing a finer-grained characterization of brain differences between case and control subjects (5).