Objective: The authors' goal was to determine whether patients with schizophrenia differ from comparison subjects in regional brain volumes and whether these differences are similar in male and female subjects.
Method: They conducted a systematic search for structural magnetic resonance imaging (MRI) studies of patients with schizophrenia that reported volume measurements of selected cortical, subcortical, and ventricular regions in relation to comparison groups. They carried out a meta-analysis of the volumes of these regions in the patients with schizophrenia and the comparison subjects using a random effects model; they also used random effects regression analysis to examine the influence of gender on effect sizes.
Results: Fifty-eight studies were identified as suitable for analysis; these studies included 1,588 independent patients with schizophrenia. Assuming a volume of 100% in the comparison group, they found that the mean cerebral volume of the subjects with schizophrenia was smaller (98%), but the mean total ventricular volume of the subjects with schizophrenia was greater (126%). Relative to the cerebral volume differences, the regional volumes of the subjects with schizophrenia were 94% in the left and right amygdala, 94% in the left and 95% in the right hippocampus/amygdala, and 93% in the left and 95% in the right parahippocampus. Relative to the global ventricular system differences, the largest differences in ventricular subdivisions were in the right and left body of the lateral ventricle, where the volumes of schizophrenic subjects were 116% and 116%, respectively. For most regions, effect size was not significantly related to gender.
Conclusions: Regional structural differences in patients with schizophrenia include bilaterally reduced volume of medial temporal lobe structures. There is a need for greater integration of results from structural MRI studies to avoid redundant research activity.