Abstract
Investigation in posttraumatic stress disorder (PTSD) shows a negative association between patients’ degrees of acceptance (the willingness to face unwanted private experiences while pursuing one’s values and goals) and those of clinical symptom severity, suggesting that experiential acceptance is a protective factor of symptoms or an early indicator of resilience after trauma. However, neural mechanisms involved in the relationship between these two variables have yet to be elucidated. Thus, we here investigate whether there are neural mechanisms mediating such relationship using whole-brain voxel-level mediation analysis with seed-based resting-state functional connectivity (RSFC) maps generated by hippocampal subregion seeds in accident survivors (n = 33). We found that the correlation between patients’ acceptance and symptom severity was mediated by the RSFC strength between left hippocampal body and left lateral occipital cortex adjacent to superior parietal cortex, the areas related to flashbacks. Our result provides novel evidence that hippocampal RSFC mediates the effect of experiential acceptance on posttraumatic stress symptom severity. If further refined and validated, the finding may aid to the identification of biomarkers to intervention and prevention programs for patients with PTSD.
Highlights
Posttraumatic stress disorder (PTSD) is a debilitating condition that develops after encountering traumatic events, such as direct exposure to life-threatening accidents, sexual or physical assaults, domestic violence, or indirect witnessing others experience traumatic events
Using the Mediation Toolbox, we investigated whether the effect of the acceptance (X) on the posttraumatic stress symptoms (PTSS) severity (Y) was explained indirectly by the resting-state functional connectivity (RSFC) strength (M), the seed-tovoxel functional connectivity to each of hippocampal subregions (Figure 1B)
The map of the path a × b effect showed a negative mediation in the left LOC/SPC, resulting from the acceptanceassociated reductions in RSFC and a positive RSFC–PTSS severity relationship. This is the first investigation to examine whether there are neural mechanisms mediating the impact of the acceptance on PTSS severity
Summary
Posttraumatic stress disorder (PTSD) is a debilitating condition that develops after encountering traumatic events, such as direct exposure to life-threatening accidents, sexual or physical assaults, domestic violence, or indirect witnessing others experience traumatic events. Given the high prevalence of the disorder, the detection of reliable early indicators of vulnerability and the development of early interventions have received increasing interest in recent years and have contributed the understanding of the pathophysiological mechanisms of PTSD. In this regard, many researchers have used neuroimaging features to determine vulnerability- and disease-specific neural markers in an attempt to forecast the onset or course of the disorder. The investigation demonstrates that posttraumatic stress symptoms (PTSS) are developed and maintained by habitual efforts to avoid trauma-related thoughts, emotions, and memories, suggesting that they may be decreased by acceptance as psychological flexibility [4,5,6]. It is suggested that lower levels of experiential acceptance may be one of the individual difference factors associated with vulnerability to PTSD [7, 8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
