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Front. Psychiatry | doi: 10.3389/fpsyt.2018.00272

Deterioration in Global Organization of Structural Brain Networks in Schizophrenia: A Diffusion MRI Tractography Study

 Seung-Hyun Shon1, Woon Yoon1, Harin Kim2,  SungWoo Joo3,  Yangsik Kim4 and  Jungsun Lee1*
  • 1Psychiatry, Asan Medical Center, South Korea
  • 2Psychiatry, Armed Forces Capital Hospital, South Korea
  • 3Psychiatry, Republic of Korea Marine Corps, South Korea
  • 4Graduated School of Medical Science and Engineering, Korea Advanced Institute of Science & Technology (KAIST), South Korea

Schizophrenia is a heterogenous neuropsychiatric disorder with varying degrees of altered connectivity in a wide range of brain areas. Network analysis using graph theory allows researchers to integrate and quantify relationships between widespread changes in a network system. This study examined the organization of brain structural networks by applying diffusion MRI, probabilistic tractography, and network analysis to 48 schizophrenia patients and 24 healthy controls. T1-weighted MR images obtained from all participants were parcellated into 87 regions of interests (ROIs) according to a prior anatomical template and registered to diffusion-weighted images (DWI) of the same subjects. Probabilistic tractography was performed to obtain sets of white matter tracts between any two ROIs and determine the connection probabilities between them. Connectivity matrices were constructed using these estimated connectivity probabilities, and several network properties related to network effectiveness were calculated. Global efficiency, local efficiency, clustering coefficient, and mean connectivity strength were significantly lower in schizophrenia patients (p=0.042, p=0.011, p=0.013, p=0.046). Mean betweenness centrality was significantly higher in schizophrenia (p=0.041). Comparisons of node wise properties showed trends towards differences in several brain regions. Nodal local efficiency was consistently lower in the basal ganglia, frontal, temporal, cingulate, diencephalon, and precuneus regions in the schizophrenia group. Inter-group differences in nodal degree and nodal betweenness centrality varied by region and showed inconsistent results. Robustness was not significantly different between the study groups. Significant positive correlations were found between t-score of color trails test part-1 and local efficiency and mean connectivity strength in the patient group. The findings of this study suggest that schizophrenia results in deterioration of the global network organization of the brain and reduced ability for information processing.

Keywords: Schizophrenia, diffusion MRI, Probabilistic Tractography, Network analysis, connectivity

Received: 10 Mar 2018; Accepted: 05 Jun 2018.

Edited by:

Błażej Misiak, Wroclaw Medical University, Poland

Reviewed by:

Chuanjun Zhuo, Tianjin Medical University General Hospital, China
DANIEL BERGE, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Spain  

Copyright: © 2018 Shon, Yoon, Kim, Joo, Kim and Lee. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: MD, PhD. Jungsun Lee, Asan Medical Center, Psychiatry, Seoul, South Korea, js_lee@amc.seoul.kr