Frontal EEG asymmetry during symptom provocation predicts subjective responses to intrusions in survivors with and without PTSD

Abstract

Studies suggest that frontal alpha asymmetry is closely linked to psychological adjustment following stressful experiences, such that more left-sided frontal activation during symptom provocation might predict lower levels of posttraumatic stress disorder (PTSD). Here, we tested whether frontal asymmetry at rest and during exposure to neutral, positive, negative, and trauma-related images would be associated with PTSD, and particularly with characteristic reexperiencing symptoms. Symptoms were assessed in trauma victims with (n 5 24) and without PTSD (n 5 15), using both retrospective measures and 1-week ambulatory assessments with a diary and a smartphone. While resting frontal asymmetry was unrelated to all retrospective measures, left-sided activation in response to the negative picture correlated with lower levels of psychopathology. Left-sided activation in the trauma-related picture condition was more specifically associated with less emotionally intense intrusions and responses to viewing the picture, even when corrected for other symptoms of psychopathology. These effects tended to increase when participants with possible overreporting tendencies were removed from the analyses. Moreover, trauma victims without PTSD (i.e., relatively more resilient individuals) displayed higher left-sided frontal activation in response to the negative picture, also when compared with a third group of healthy, trauma-free individuals (n 5 15). Our findings suggest that statedependent changes in frontal asymmetry could serve as a biological marker of PTSD symptoms and could eventually be used for diagnostic purposes or as a target for neuromodulation interventions. Future studies should establish whether this marker can serve as an early predictor of psychopathology in recently traumatized individuals. K E Y W O R D Sdiary, frontal alpha asymmetry, intrusions, posttraumatic stress disorder, symptom provocation | IN TRO DUCT IO NA small, yet nontrivial proportion of individuals who have experienced aversive life events develop trauma-related psychopathology, such as posttraumatic stress disorder (PTSD). These trauma victims suffer from severe reexperiencing symptoms (e.g., intrusions, nightmares), avoidance of cues related to the trauma, altered mood and cognition, as well as exaggerated general arousal and reactivity (American Psychiatric Association, 2013). Since the diagnosis of PTSD essentially depends on self-report (Rosen & Lilienfeld, 2008) and its symptoms are only modestly related to objective trauma severity (

The Electrical Aftermath: Brain Signals of Posttraumatic Stress Disorder Filtered Through a Clinical Lens

“…Finally, type of trauma experience may play a role in heterogeneity of EEG results. Although PTSD+ and PTSD− combat veterans do not differ in frontal or parietal alpha asymmetry (47), other studies indicate that PTSD− who have experienced other types of traumatic events (accidents and witness to injury/death) similar to PTSD+ exhibit greater left frontal alpha asymmetry than PTSD+, a pattern thought to reflect resilience, or protection against deleterious effects of stress (42, 43, 102). Perhaps prolonged exposure to certain types of trauma such as combat alters brain function regardless of the degree of clinical symptoms experienced, although more research is warranted to test this hypothesis.…”

“…Increased trauma severity in boys is associated with increased left frontal asymmetry (40); however, PTSD+ and PTSD− do not differ in males with a history of combat-related trauma (47). Mixed-gender samples also show conflicting findings, with PTSD+/PTSD− trauma-exposed individuals exhibiting greater left frontal asymmetry than PTSD− non-exposed participants (43), PTSD+ showing similar asymmetry patterns as PTSD− without traumatic histories (103), and non-significant relationships between frontal asymmetry and trauma, depression, and anxiety severity (100). Lack of consistent findings could be related to: 1) sex differences in frontal asymmetry previously reported in the literature, with depression linked to left frontal asymmetry in men but right frontal asymmetry in women (154), divergent patterns that may be obscured by not directly comparing males and females in statistical analyses; 2) use of a Cz reference montage (100), shown to be the least consistent in producing reliable asymmetry results (152); and 3) recruitment of “super controls” who differ on various personality/mood variables from PTSD+ individuals (103).…”

“…Thus, with the context of active tasks, it would be expected that PTSD+ status and/or severity is associated with greater relative right frontal asymmetry, reflective of heightened withdrawal-related motivation/negative emotion processing. Indeed, studies demonstrate that higher right frontal asymmetry is linked to: 1) more severe PTSD, rumination, and depression symptoms when viewing negative images (43); 2) greater emotional intensity and physical reactions to trauma images (43); and 3) PTSD+ during trauma image viewing, compared to PTSD− (42).…”

Frontal EEG alpha asymmetry and emotion: From neural underpinnings and methodological considerations to psychopathology and social cognition

“…Among these considerations are several particularly influential issues (Smith et al, 2017): (a) the choice of reference (or CSD transformation), (b) the selection of methods for handling artifacts, (c) using designs with resting state versus experimental challenges, and (d) specifying models explicitly for testing mediating and moderating relationships of frontal asymmetry with individual differences or experimental manipulations. In this issue, several articles include exemplary treatment of these issues including the use of the CSD transformation (Rodrigues, M€ uller, M€ uhlberger, & Hewig, 2018;Smith, Cavanagh, & Allen, 2018) and experimental state manipulations (Meyer et al, 2018;Nelson, Kessel, Klein, & Shankman, 2018;Rodrigues et al, 2018;Schmid, Hackel, Jasperse, & Amodio, 2018;Wacker, 2018).…”

A review of hippocampal activation in post‐traumatic stress disorder

“…Some models suggest that the hippocampus plays a primary role mainly in early encoding and retrieval (Bergstrom, ; Frankland & Bontempi, ), with others purporting that the hippocampus is continuously involved in shaping memory retrieval over time (Bergstrom, ; Nadel & Moscovitch, ). Whether hippocampus is critical solely to original encoding, or encoding and maintenance of memories, both the original encoding of traumatic memory and maintenance (expressed as intrusive symptoms) have been postulated as key mechanisms involved in PTSD development (Meyer et al, ). Hence, research on neural correlates of memory processes in the hippocampus is highly relevant to elucidation of PTSD pathophysiology.…”