Schizophrenia patients show significant subcortical brain abnormalities. We examined these abnormalities using automated image analysis software and provide effect size estimates for prospective multi-scanner schizophrenia studies. Subcortical and intracranial volumes were obtained using FreeSurfer 5.0.0 from high-resolution structural imaging scans from 186 schizophrenia patients (mean age±S.D.=38.9±11.6, 78% males) and 176 demographically similar controls (mean age±S.D.=37.5±11.2, 72% males). Scans were acquired from seven 3-Tesla scanners. Univariate mixed model regression analyses compared between-group volume differences. Weighted mean effect sizes (and number of subjects needed for 80% power at α=0.05) were computed based on the individual single site studies as well as on the overall multi-site study. Schizophrenia patients have significantly smaller intracranial, amygdala, and hippocampus volumes and larger lateral ventricle, putamen and pallidum volumes compared with healthy volunteers. Weighted mean effect sizes based on single site studies were generally larger than effect sizes computed based on analysis of the overall multi-site sample. Prospectively collected structural imaging data can be combined across sites to increase statistical power for meaningful group comparisons. Even when using similar scan protocols at each scanner, some between-site variance remains. The multi-scanner effect sizes provided by this study should help in the design of future multi-scanner schizophrenia imaging studies.
Bibliographical noteFunding Information:
We are thankful to Liv McMillan for overall study coordination, Harry Mangalam, Joseph Farran, and Adam Brenner, for administering the University of California, Irvine High-Performance Computing cluster, and to the research subjects for their participation. This work was supported by the National Center for Research Resources at the National Institutes of Health (Grant nos. NIH 1 U24 RR021992 ( Function Biomedical Informatics Research Network ) and NIH 1 U24 RR025736-01 ( Biomedical Informatics Research Network Coordinating Center ; http://www.birncommunity.org ). The funding sources had no role in the study design, data collection, analysis, and interpretation of the data.
- Effect size
- Magnetic resonance imaging (MRI)