The functional connectome in posttraumatic stress disorder

Isabella A Breukelaar; Richard A Bryant; Mayuresh S Korgaonkar

doi:10.1016/j.ynstr.2021.100321

The functional connectome in posttraumatic stress disorder

Neurobiol Stress. 2021 Mar 31:14:100321. doi: 10.1016/j.ynstr.2021.100321. eCollection 2021 May.

Authors

Isabella A Breukelaar^{1

2}, Richard A Bryant^{1

2}, Mayuresh S Korgaonkar^{1

3

4}

Affiliations

¹ Brain Dynamics Centre, Westmead Institute for Medical Research, University of Sydney, Westmead, NSW, Australia.
² School of Psychology, University of New South Wales, Sydney, Australia.
³ Discipline of Psychiatry, Sydney Medical School, Westmead, NSW, Australia.
⁴ School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.

Abstract

Background: Previous fMRI studies of posttraumatic stress disorder (PTSD) have investigated region-specific alterations in intrinsic connectivity but connectome-wide changes in connectivity are yet to be characterized. Understanding the neurobiology of this is important to develop novel treatment interventions for PTSD. This study aims to identify connectome-wide disruptions in PTSD to provide a more comprehensive analysis of nseural networks in this disorder.

Methods: A functional MRI scan was completed by 138 individuals (67 PTSD and 71 non-trauma-exposed healthy controls [HC]). For every individual, inter-regional intrinsic functional connectivity was estimated between 436 brain regions, comprising intra and inter-network connectivity of eight large-scale brain networks. Group-wise differences between PTSD and HC were investigated using network-based statistics at a family-wise error rate of p < 0.05. Significant network differences were then further investigated in 27 individuals with trauma exposure but no PTSD [TC]).

Results: Compared to HC, PTSD displayed lower intrinsic functional connectivity in a network of 203 connections between 420 regions within and between mid-posterior default mode, central executive, limbic, visual and somatomotor regions. Additionally, PTSD displayed higher connectivity across a network of 50 connections from thalamic and limbic to sensory and default-mode regions. Connectivity in TC in both these networks was intermediate and significantly different to PTSD and HC.

Conclusion: A large-scale imbalance between hypoconnectivity of higher-order cortical networks and hyperconnectivity of emotional and arousal response systems seems to occur on a sliding scale from trauma exposure to clinical manifestation as PTSD. Novel interventions that target this systemic functional imbalance could provide potential mitigation of PTSD.

Keywords: Connectome; Functional connectivity; Network; Neuropathology; Posttraumatic stress disorder; fMRI.