Background: The shared neuropathological characteristics of patients with schizophrenia and their siblings might represent intermediate phenotypes that could be used to investigate genetic susceptibility to the illness. We sought to discover gray matter volume differences in patients with schizophrenia and their unaffected siblings with voxel-based morphometry (VBM).
Methods: We recruited antipsychotic drug-naive, first-episode schizophrenia (FES) patients, their unaffected siblings and age-, sex- and handedness-matched healthy controls. We used VBM to investigate differences in gray matter volume among the 3 groups.
Results: There were significant gray matter volumetric differences among the 3 groups in bilateral hippocampal and parahippocampal gyri, bilateral middle temporal gyri, and superior temporal gyri (FDR p<0.05). Patients had significant regional gray matter reduction in all regions listed above compared with healthy volunteers, and their gray matter volume in the right hippocampus and parahippocampus was also lower than the sibling group. The sibling group had significantly lower volumes compared to healthy individuals only in the left middle temporal gyrus, and volume of this region was not different between siblings and patients.
Conclusions: Our findings confirm and extend previous VBM analyses in schizophrenia and it indicate that schizophrenia may be characterized by an abnormal development of cerebral lateralization. Furthermore, these data argue that patients and their unaffected siblings might share decreases in the gray matter volume of the left middle temporal gyrus, and this regional reduction might be a potential endophenotype for schizophrenia.
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