Abstract
In order to clarify the implications of morphological brain changes in development of schizophrenia, we have made extensive comparisons of brain morphology using MRI between established schizophrenia and schizotypal disorder, a schizophrenia-spectrum disorder without overt and sustained psychotic episode. Compared with controls, bilateral volumes of the amygdala, hippocampus and posterior superior temporal gyrus were reduced comparably in both schizotypal and schizophrenia patients. Total prefrontal grey matter was smaller bilaterally in schizophrenia patients than in controls, whereas schizotypal patients had larger right prefrontal grey matter than controls. In schizophrenia patients, the bilateral superior frontal, inferior frontal and straight gyri, and the left middle frontal gyrus were smaller than those in controls, while schizotypal patients had larger bilateral middle frontal gyri and smaller right straight gyrus. In white matter, decreased volume of the anterior limb of the internal capsule, a fiber bundle connecting the frontal cortex and thalamus, was found bilaterally in schizophrenia but only on the right in schizotypal disorder. These findings suggest that volume reductions in the medial and postero-lateral temporal regions are the common morphological substrates for the schizophrenia-spectrum which presumably represent the vulnerability. Additional widespread involvement of the prefrontal cortex might lead to the loss of inhibitory control in other brain regions and play a critical role in the manifestation of overt psychosis. [J Physiol Sci. 2006;56 Suppl:S38]
