Brain Abnormality in Schizophrenia. A Systematic and Quantitative Review of Volumetric Magnetic Resonance Imaging Studies

Background: Numerous in vivo brain imaging studies suggest that cerebral structure is abnormal in schizophrenia, but implicate different regions to varying extents.

Method: We identified published MRI studies in schizophrenia with searches of the computerised literature and key journals. Reports giving the volumes of cortical structures in people with schizophrenia and controls were included. The percentage differences in volumes were calculated and the median taken as a summary measure for each brain region.

Results: Forty relevant studies were identified. The median percentage volume differences revealed overall reductions in the whole brain (3%), temporal lobe (6% left, 9.5% right), and the amygdala/ hippocampal complex (6.5%, 5.5%); and increases in the lateral ventricles (44%, 36%), that were greatest in the body and occipital horns. Segmentation studies suggest that grey matter is reduced but that white matter volumes may actually be increased. In men, substantial reductions were also evident in the amygdala and hippocampus, as well as the largest reductions of all in the parahippocampus (14%, 9%). Few studies gave figures for women alone.

Conclusions: Several brain structures in schizophrenia are affected to a greater extent than expected from overall reductions in brain volume. Further studies are required in affected women, and to try to identify clinical and aetiological associations of these findings.