Posttraumatic stress symptom dimensions and brain responses to startling auditory stimuli in combat veterans.

Abstract

Posttraumatic stress disorder (PTSD) is marked by alterations in emotional functioning, physiological reactivity, and attention. Neural reactivity to acoustic startle stimuli can be used to understand brain functions related to these alterations. Investigations of startle reactivity in PTSD have yielded inconsistent findings, which may reflect the heterogeneity of the disorder. Furthermore, little is known of how the common cooccurrence of mild traumatic brain injury (mTBI; i.e., concussion) may influence neural reactivity. We examined the event-related potentials (ERPs) of combat veterans (n = 102) to acoustic startle probes delivered during viewing of pleasant, neutral, unpleasant, and combat-related pictures. Interview-based assessments yielded dimensional characterizations of PTSD and mTBI. The P3 ERP response to startle probes was reduced during all affective relative to neutral pictures but failed to be associated with a PTSD diagnosis. However, two separable domains of PTSD symptomatology were associated with startle ERPs regardless of the picture conditions. Maladaptive avoidance was associated with smaller N1, P2, and P3 amplitudes, while intrusive reexperiencing was associated with larger P2 amplitudes. There were no main effects of mTBI. Findings suggest that level of symptomatology rather than a formal diagnosis of PTSD better explains alterations in neural reactivity after traumatic events, while mild brain injuries have little impact. Avoidance symptoms of PTSD may dampen neural functions that facilitate reorientation to threat while intrusive reexperiencing of traumatic events appears to heighten sensory reactivity. Considering specific aspects of symptomatology provides insight into the neural basis of trauma-related psychopathology and may help guide individualization of clinical interventions.

Somatomotor Beta Bursts Mediate the Negative Impact of PTSD Severity on Conflict Monitoring

“…Our primary intention in the current report was to investigate if beta burst events could index response control dysfunction related to posttraumatic stress symptomatology in combat-exposed veterans. In line with prior reports of brain activation in combat-exposed veterans (Marquardt et al, 2021), we found that BBR predicted PTSD symptom severity but failed to be associated with a categorical diagnosis of PTSD. It is possible that the association with symptoms merely reflects an increase in statistical power with continuous as opposed to dichotomous measures (Altman & Royston, 2006; Lazic, 2008); however, the benefit of dimensional measures mirrors a recent focus on less reliance on diagnostic categories in psychopathology research.…”

“…For example, the DSM-5 (2013) includes severity indicators for many disorders, consistent with the critical role that disorder severity plays in clinical management. The lack of an association of BBR with mTBI adds to the growing body of evidence that many reported consequences of military mTBI can be attributed to psychopathology other than mTBI, including PTSD (Disner et al, 2017; Marquardt et al, 2021).…”

“…Study procedures were approved by the Institutional Review Boards at the VAHCS and the University of Minnesota, and study participants gave written informed consent prior to undergoing the study procedures. This sample has been previously reported in (Davenport et al, 2016; Disner et al, 2018; Marquardt et al, 2021); none of these publications have examined data from the flanker paradigm. Error trial analysis considered a smaller subset of these participants (n = 106) who had at least ten error trials with clean EEG (all n = 130 subjects had sufficient correct trial data).…”

Impact of reduced‐dimensionality independent components analysis on event‐related potential measurements

“…Thus if there is greater noise in the single‐trial mean amplitude measurements (i.e., a larger standard deviation), the SME will be larger, indicating lower precision in single‐trial mean amplitudes. Finally, much ERP research seeks to examine the relationship of brain potentials with individual differences (Dong et al, 2015; Marquardt et al, 2021), which requires reliable ERP measures (though see: Hedge et al, 2018). As discussed in Luck et al (2020), classical reliability is sensitive to the degree of heterogeneity in a given sample such that greater heterogeneity leads to greater reliability estimates even when the precision of the measurement (e.g., SME) is held constant.…”

Inefficient Attentional Control Explains Verbal-Memory Deficits Among Military Veterans With Posttraumatic Reexperiencing Symptoms

“…An exclusive focus on categorical definitions of PTSD may obscure which symptom domains are predictive of functional outcomes and limit statistical power for detecting associations with cognitive mechanisms (Cuthbert, 2005;Grove, 1991). Factor analyses suggest the existence of separate PTSD symptom dimensions: intrusive reexperiencing, avoidance, dysphoric mood, and hyperarousal (Yufik & Simms, 2010), which appear to more closely track with brain-based systems than the PTSD diagnosis alone (Lieberman et al, 2017;Marquardt et al, 2018Marquardt et al, , 2021. Therefore, investigating how specific symptom dimensions of PTSD map onto memory deficits may clarify what aspects of the disorder relate to the consolidation and retrieval of verbal material.…”