ABSENCE OF REGIONAL HEMISPHERIC VOLUME ASYMMETRIES IN FIRST-EPISODE SCHIZOPHRENIA

Objective: The goal of this study was to determine whether patients ex periencing their first episode of schizophrenia differ from healthy su bjects in regional cerebral hemispheric volumes or asymmetries. Method : Regional volumes corresponding to prefrontal, premotor, sensorimotor , occipitoparietal, and temporal lobes in each hemisphere were measure d on contiguous coronal magnetic resonance images in 70 patients exper iencing their first episode of schizophrenia and in 51 healthy compari son subjects. Results: Patients did not differ from the comparison sub jects in regional or total hemispheric volumes, but they had abnormal hemispheric asymmetries. Subjects in the comparison group had signific ant lateral asymmetries in each region: their occipitoparietal and ser sorimotor regions were larger on the left, and their premotor, prefron tal, and temporal regions were larger on the right. Patients lacked la teral asymmetries and showed significantly less asymmetry than healthy subjects in occipitoparietal, premotor, and prefrontal regions. Absen ce of the normal asymmetry was more common among Patients initially di agnosed with the undifferentiated than with the paranoid subtype of sc hizophrenia and was associated with more severe negative symptoms amon g men. Asymmetries were related to sex and handedness regardless of di agnosis; specifically, dextral men showed more asymmetry than nondextr al men or dextral women. Conclusions: The absence of normal hemispheri c asymmetries suggests an anomaly in the development of laterally spec ialized cerebral systems in schizophrenia, and this may be associated with an initial presentation of nonparanoid psychosis.