Summary: White matter functional connectivity distributions may contribute to working memory and processing speed impairments in schizophrenia.

Source: Vanderbilt University

Schizophrenia, a disturbance of functional connections within brain networks, has been extensively studied by MRI. However, functional alterations involving white matter (WM) have not previously been investigated, especially during tasks.

Yurui Gao, Ph.D., Neil Woodward, Ph.D., John Gore, Ph.D., and colleagues analyzed resting state and task fMRI images from 84 patients with schizophrenia and 67 controls to examine functional connectivity (FC). They compared FC between 46 WM bundles and 82 cortical regions, and the FC density of each WM bundle was compared between groups.

FC measures were found to be lower in people with schizophrenia relative to controls for external capsule, cingulum, uncinate fasciculus and corpus callosum under the rest or task condition, and higher in the posterior corona radiata and posterior thalamic radiation during the task condition.

Functional alterations involving white matter (WM) have not previously been investigated, especially during tasks. Image is in the public domain

The findings, reported in Schizophrenia Research, suggest functional abnormalities in patients’ WM are heterogeneous, possibly reflecting underlying mechanisms like structural damage, functional compensation and excessive effort on task, and WM FC disruption may contribute to impairment of working memory and processing speed.

About this schizophrenia research news

Author: Emily Stembridge
Source: Vanderbilt University
Contact: Emily Stembridge – Vanderbilt University
Image: The image is in the public domain

Original Research: Closed access.
“Lower functional connectivity of white matter during rest and working memory tasks is associated with cognitive impairments in schizophrenia” by Yurui Gao et al. Schizophrenia Research


Abstract

Lower functional connectivity of white matter during rest and working memory tasks is associated with cognitive impairments in schizophrenia

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Background

Schizophrenia can be understood as a disturbance of functional connections within brain networks. However, functional alterations that involve white matter (WM) specifically, or their cognitive correlates, have seldomly been investigated, especially during tasks.

Methods

Resting state and task fMRI images were acquired on 84 patients and 67 controls. Functional connectivities (FC) between 46 WM bundles and 82 cortical regions were compared between the groups under two conditions (i.e., resting state and during working memory retention period). The FC density of each WM bundle was then compared between groups. Associations of FC with cognitive scores were evaluated.

Results

FC measures were lower in schizophrenia relative to controls for external capsule, cingulum (cingulate and hippocampus), uncinate fasciculus, as well as corpus callosum (genu and body) under the rest or the task condition, and were higher in the posterior corona radiata and posterior thalamic radiation during the task condition. FC for specific WM bundles was correlated with cognitive performance assessed by working memory and processing speed metrics.

Conclusions

The findings suggest that the functional abnormalities in patients’ WM are heterogeneous, possibly reflecting several underlying mechanisms such as structural damage, functional compensation and excessive effort on task, and that WM FC disruption may contribute to the impairments of working memory and processing speed. This is the first report on WM FC abnormalities in schizophrenia relative to controls and their cognitive associates during both rest and task and highlights the need to consider WM functions as components of brain functional networks in schizophrenia.



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