Presentation Information
[O-9-06]Early psychosis is characterized by white matter abnormalities in fiber structures supporting local connectivity
*YOSHITO SAITO1, Warda T. Syeda1,2, Cassandra M.J. Wannan1,3,4, Yasmin Gurleyen1, Marta Rapado-Castro1,5, Maria A. Di Biase1,6,7,8, Remika Mito1, Christos Pantelis1,9,10 (1.Department of Psychiatry, The University of Melbourne(Australia), 2.Melbourne Brain Centre Imaging Unit, Department of Radiology, The University of Melbourne(Australia), 3.Centre for Youth Mental Health, The University of Melbourne(Australia), 4.Orygen(Australia), 5.Department of Child and Adolescent Psychiatry, Hospital General Universitario Gregorio Marañón, Universidad Complutense(Spain), 6.Systems Group, Department of Psychiatry, The University of Melbourne(Australia), 7.Stem Cell Disease Modelling Lab, Department of Anatomy and Physiology, The University of Melbourne(Australia), 8.Department of Psychiatry, Brigham and Women’s Hospital, Harvard Medical School(United States of America), 9.Western Centre for Health Research & Education, University of Melbourne & Western Health, Sunshine Hospital(Australia), 10.Monash Institute of Pharmaceutical Sciences (MIPS), Monash University(Australia))
Keywords:
Early psychosis,Superficial white matter,Diffusion-weighted imaging,Cognition,Schizophrenia-spectrum disorders
Background
While long-range white matter (WM) connectivity has been widely studied in schizophrenia-spectrum disorders (SSDs), recent evidence highlights the importance of local network disruptions. Superficial white matter (SWM), located between cortex and WM, comprises short association fibers supporting local connectivity. As SWM matures in the latter stages of development relative to deep WM structures, it may be particularly vulnerable to neurodevelopmental disruptions observed in SSDs. However, its complex fiber architecture and proximity to the cortex pose challenges for conventional diffusion tensor imaging.
Methods To overcome these limitations, we applied an advanced diffusion MRI approach to assess fiber density (FD) in the SWM of 78 individuals with early psychosis (age 22.0±3.0, 45% female) and 78 controls (age 21.8±3.2, 45% female).
Results Early psychosis individuals showed widespread reductions in SWM FD, particularly in occipital, temporal, parietal, and insular regions, whereas no significant group differences were detected using fractional anisotropy from tensor imaging. FD reductions were associated with reduced cortical thickness (p<0.0005, r=0.32) and surface area (p=0.006, r=0.23), indicating coordinated cortex-WM alterations. SWM FD was associated with processing speed (p=0.0029) and working memory (p=0.048). Further, SWM mediated the relationship between cortical structure and processing speed in frontal and parietal regions.
Conclusions These findings highlight SWM, supporting local network connectivity, as a tissue compartment showing widespread alterations in SSDs. By implementing an advanced diffusion MRI technique, we were able to assess changes that were specific to the complex WM at the cortical boundary, and to demonstrate functionally important alterations in this difficult-to-characterize tissue compartment.
While long-range white matter (WM) connectivity has been widely studied in schizophrenia-spectrum disorders (SSDs), recent evidence highlights the importance of local network disruptions. Superficial white matter (SWM), located between cortex and WM, comprises short association fibers supporting local connectivity. As SWM matures in the latter stages of development relative to deep WM structures, it may be particularly vulnerable to neurodevelopmental disruptions observed in SSDs. However, its complex fiber architecture and proximity to the cortex pose challenges for conventional diffusion tensor imaging.
Methods To overcome these limitations, we applied an advanced diffusion MRI approach to assess fiber density (FD) in the SWM of 78 individuals with early psychosis (age 22.0±3.0, 45% female) and 78 controls (age 21.8±3.2, 45% female).
Results Early psychosis individuals showed widespread reductions in SWM FD, particularly in occipital, temporal, parietal, and insular regions, whereas no significant group differences were detected using fractional anisotropy from tensor imaging. FD reductions were associated with reduced cortical thickness (p<0.0005, r=0.32) and surface area (p=0.006, r=0.23), indicating coordinated cortex-WM alterations. SWM FD was associated with processing speed (p=0.0029) and working memory (p=0.048). Further, SWM mediated the relationship between cortical structure and processing speed in frontal and parietal regions.
Conclusions These findings highlight SWM, supporting local network connectivity, as a tissue compartment showing widespread alterations in SSDs. By implementing an advanced diffusion MRI technique, we were able to assess changes that were specific to the complex WM at the cortical boundary, and to demonstrate functionally important alterations in this difficult-to-characterize tissue compartment.