Altered default mode network configuration in posttraumatic stress disorder after earthquake: A resting-stage functional magnetic resonance imaging study

Abstract

The neural substrates of posttraumatic stress disorder (PTSD) are still not fully elucidated. Hence, this study is to explore topological alterations of the default mode network (DMN) in victims with PTSD after a magnitude of 8.0 earthquake using resting-state functional magnetic resonance imaging (rs-fMRI).This study was approved by the local ethical review board, and all participants signed written informed consent. Sixty-two PTSD victims from the 2008 Sichuan earthquake and 62 matched exposed controls underwent rs-fMRI. PTSD was diagnosed by Clinician-Administered PTSD Scale, and underwent PTSD Checklist-Civilian Version for symptom scoring. The DMN was analyzed by using graph theoretical approaches. Further, Pearson correlation analysis was performed to correlate neuroimaging metrics to neuropsychological scores in victims with PTSD.Victims with PTSD showed decreased DMN functional connectivity strength between the right superior frontal gyrus and left inferior parietal lobule (IPL), and showed increased functional connectivity between the right IPL and precuneus or left posterior cingulate cortex. It was also found that victims with PTSD exhibited decreased nodal efficiency in right superior frontal gyrus and precuneus, and increased nodal efficiency in right hippocampus/parahippocampus. Apart from that, PTSD showed higher nodal degree in bilateral hippocampus/parahippocampus. In addition, the functional connectivity strength between the right IPL and precuneus correlated negatively to the avoid scores (r = -0.26, P = .04).This study implicates alteration of topological features on the DMN in PTSD victims after major earthquake, and provides new insights into DMN malfunction in PTSD based on graph theory.

Figure 1

Decreased (blue) and increased (red) functional connectivity of DMN in PTSD compared with non-PTSD. FPA correction, P < .005. BA = Brodmann Area, FC = functional connectivity, FPA =  false-positive adjustment, IPL = inferior parietal lobule, Non-PTSD = non-posttraumatic stress disorder, PCC = posterior cingulate cortex, PCu = precuneus, PTSD = posttraumatic stress disorder, SFG = superior frontal gyrus.

Figure 2

Nodal efficiency comparison between PTSD and non-PTSD, significant level P < .01. Victims with PTSD showed decreased nodal efficiency in right SFG and PCu-BA7-vertral, and increased nodal efficiency in right H/PH compared with non-PTSD. (∗ denote significant differences between the 2 groups). BA = Brodmann Area, H/PH = hippocampus/parahippocampus, Non-PTSD = nonposttraumatic stress disorder, PCu = precuneus, PTSD = posttraumatic stress disorder, SFG = superior frontal gyrus.

Figure 3

Nodal degree comparison between PTSD and non-PTSD, significant level P < .01. PTSD showed higher nodal degree in bilateral H/PH compared with non-PTSD. (∗ denote significant differences between the 2 groups). H/PH = hippocampus/parahippocampus, PTSD = posttraumatic stress disorder, Non-PTSD = nonposttraumatic stress disorder.

Figure 4

Correlation between the score of avoidance and FC strengh (P < .05). The FC strength between right IPL (BA40) and PCu (BA31) correlate negatively to avoidance score. FC = functional connectivity, IPL = inferior parietal lobule, PCu = precuneus.