Interactive effects of polygenic risk and cognitive subtype on brain morphology in schizophrenia spectrum and bipolar disorders.

"Declarations Conflict of interestAll authors declare that they have no conflicts of interest. Ethics approvalAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by the Human Research Ethics committees of the University of New South Wales (HC12384), the South East Sydney and Illawarra Area Health Service (HREC 09/081) and St Vincent’s Hospital (HREC/10/SVH/9). Consent to participateInformed consent was obtained from all individual participants included in the study. Consent for publicationNot applicable. Conflict of interest All authors declare that they have no conflicts of interest."

"Funding Open Access funding enabled and organized by CAUL and its Member Institutions. This study was supported by Project Grants from the Australian National Health and Medical research Council (NHMRC; APP630471 and APP1081603), and the Macquarie University’s ARC Centre of Excellence in Cognition and its Disorders (CE110001021). MJG was supported by an Australian Research Council Future Fellowship (FT0991511; 2009-13) and a R.D. Wright Biomedical Career Development Award from the NHMRC (1061875; 2014-17). MJC is supported by an NHMRC Senior Research Fellowship (1121474). OJW was supported by an Australian Government Research Training Program (RTP) Scholarship (administered by the University of New South Wales) and the Edward C Dunn Foundation Postgraduate Scholarship (administered by Neuroscience Research Australia; NeuRA). The funding bodies had no role in the design of the study, collection and analysis of data, or the decision to publish."

"High-resolution T1-weighted anatomical scans (MPRAGE) were obtained on a Philips 3 T Achieva TX scanner (Philips Healthcare, Best, The Netherlands) housed at Neuroscience Research Australia (Randwick, NSW, Australia) with a 32-channel head coil for each participant (TR 8.9 ms, TE 4.1 ms, field of view 240 mm, matrix 268 × 268, 200 sagittal slices, slice thickness 0.9 mm, no gap). All scans successfully passed a quality assessment protocol in which a radiologist reviewed all scans, and an additional visual inspection for gross artefacts and movements (presence of excessive ringing that would not allow identification of two adjacent brain regions) was followed by an automated quality control using the Computational Anatomy Toolbox (CAT12.6, v1433; http://dbm.neuro.uni-jena.de/cat/index.html) for SPM12 (v7487; Wellcome Trust Centre for Neuroimaging, London, UK; http://www.fil.ion.ucl.ac.uk/spm) in Matlab r2014b (Mathworks Inc., Sherborn, MA, USA). Structural scans were pre-processed using CAT12 default routine for voxel-based morphometry (VBM). The VBM processing pipeline included segmentation of the scans into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF) segments that were normalized to a standard Montreal Neurological Institute (MNI152) template using the SPM's “Diffeomorphic Anatomic Registration Through Exponentiated Lie” algebra normalization (DARTEL) []. In addition, partial volume effects [], hidden Markov Random Field model [] and adaptive maximum a posteriori estimations [] were applied to the segmentation. Normalized images were additionally modulated with the Jacobian determinants of the deformation parameters. Following these steps, an additional quality control on sample homogeneity was performed to ensure there were no outlier scans with a Mahalanobis distance between mean correlations and weighted overall image quality significantly higher than the other scans. Grey matter images were smoothed with a 8 mm full width at half maximum (FWHM) Gaussian kernel for second-level (group comparison) VBM analyses. Finally, total intracranial (TIV), total GM, total WM and total CSF volumes were also extracted for each participant. Grey matter images were smoothed with a 8 mm full width at half maximum (FWHM) Gaussian kernel for second-level (group comparison) voxel-based morphology (VBM) analyses."