Longitudinal Changes in Resting-State Functional Connectivity of the Salience Network Among Individuals At-Risk for PTSD Development

Abstract

Predicting post-traumatic stress disorder (PTSD) following a traumatic event has been a focus of recent neuroimaging research in the hopes of identifying key biomarkers that contribute to the disorder’s development. One possibility relies on understanding the connectivity between intrinsic connectivity networks (ICNs), including the salience network (SN). Prior research has consistently identified hyperconnectivity among SN regions among those with chronic PTSD, and this study aimed to examine the role of SN connectivity over time on PTSD symptom development. To do so, this study recruited individuals presenting to the Emergency Department with traumatic injuries to complete two resting-state fMRI scans: one at two-weeks post-trauma (T1) and one at six-months post-trauma (T2). The current analyses used an intrinsic connectivity contrast (ICC) within a SN mask of salience-related regions to assess the connectivity of particular SN regions with the entirety of the network. There were no significant relationships between T2 connectivity and total PTSD symptom severity at T2, nor was there any significant findings for the relationship between T1 connectivity and total PTSD symptom severity at T2. While the change in total PTSD symptom severity scores did not significantly relate to changes in SN connectivity over time, a significant cluster within the dACC was found to be hyperconnected with the rest of the SN for the interaction between Time and Reexperiencing symptom severity score. This result remained significant when additional covariates were added to the model. Overall, this study highlights the importance of tracking changes in neurocircuitry from the acute trauma response to chronic PTSD, suggesting that chronic exposure to reexperiencing symptoms of PTSD leads to small changes in SN connectivity that slowly rewire ICN circuitry over time.