Cerebral volume asymmetries in schizophrenia and mood disorders: a quantitative magnetic resonance imaging study

Multiple abnormalities of brain structure have been identified in schizophr enia using in vivo neuroimaging methods, but little is known about the diag nostic specificity of these abnormalities. In a prior study of first-episod e schizophrenia we found that this group lacked the normal pattern of cereb ral volume asymmetries. Data from that study were combined with data from g roups of patients with more chronic schizophrenia, and with bipolar and uni polar mood disorders, to determine the specificity of this abnormality to d iagnostic subgroups defined by syndromal status or chronicity. The total sa mple comprised 235 patients (67 healthy volunteers, 81 patients with mood d isorders or schizoaffective disorders, and 87 with schizophrenia or schizop hreniform disorders). Asymmetries of regional cerebral Volumes were measure d on coronal magnetic resonance images with 3.1-mm contiguous slices and no minal in-plane resolution of 1 mm X 1 mm. Asymmetries differed significantl y across groups in the occipitoparietal, prefrontal, and temporal regions. These asymmetries, and a composite index of asymmetry across regions ('torq ue'), all showed the same diagnostic group effect, with the schizophrenia g roup showing the least normal asymmetry, the mood disorder group intermedia te asymmetry, and the control group the most marked asymmetry. No other dia gnostic subgroup or chronicity effects were apparent. The findings support a 'continuum' rather than a 'diagnostic specificity' hypothesis, and sugges t that the reduction of normal hemispheric asymmetries may mark a neurodeve lopmental risk factor for major mental illnesses, and that some syndromal c haracteristics may be correlated with the degree of deviation from the norm al anatomic pattern. (C) 1999 Elsevier Science B.V. All rights reserved.