ABSTRACT
However, in studies of the relatives of patients it is difficult to quantify the magnitude of risk in an individual. This is less of an issue if familial risk is examined in twins, particularly those who are genetically identical but are discordant for schizophrenia. Again there have been a number of neuroimaging studies in this area. Baare et al found that in genetically identical twin pairs, schizophrenia was associated with a reduction in total cortical volume and enlarged ventricles.3 However, there also seemed to be an effect of risk on intracranial volume, so both the disorder and the degree of genetic risk appeared to have neural correlates. In another recent study in twins, Cannon et al reported that schizophrenia was associated with less grey matter in a number of regions, particularly the lateral prefrontal, parietal and temporal cortex.4 Genetic vulnerability to schizophrenia across monozygotic (MZ) and dizygotic (DZ) twins was associated with volume reductions in a different set of areas, although these overlapped with those associated with the presence of schizophrenia, particularly in the lateral prefrontal cortex. Thus, in some areas, cortical volume appeared to depend on both the individual’s genetic risk and whether they were affected by the disorder.
