The effect of hypnotically induced somatoform dissociation on the development of intrusions after an aversive film

Can Listening to a Verbal Trauma Report Induce Intrusions? - Replication of a Randomized Trial

Recent evidence suggests that indirect verbal exposure to traumatic events can be sufficient to cause intrusions and other posttraumatic stress symptoms. In this study, we used a verbal trauma report to experimentally induce intrusions and a tactile task to manipulate the putative processes underlying intrusion development. Our findings indicate that the verbal report indeed induced intrusive recall. Moreover, the verbal report induced negative mood, state anxiety, and state dissociation, with mood and state dissociation predicting intrusion development. Additionally, the tactile task interfered with intrusion formation as indicated by the primary diary measure, but not the retrospective self-report. However, these results await further replication as this and previous trials suffered from limited statistical power. The findings support the reports by trauma therapists who experience secondary traumatization. They also challenge the assumption that all intrusions develop bottom-up from low-level sensory input via sensory representations. Future studies should explore differential processes for intrusion development based on their modality.

The effectiveness of two novel approaches to prevent intrusions: A pilot study comparing Tetris_dualtask and imagery rescripting to control

BACKGROUND AND OBJECTIVES

Post-traumatic stress disorder (PTSD) is a global health problem. Although effective treatments for it exist, early interventions that prevent PTSD from developing are lacking. The aim of this pilot analogue trauma study was to compare the effects of two potential early intervention strategies, namely Tetris_dualtask and imagery rescripting (IR) to a no-intervention control group on intrusion frequency and the vividness and emotionality of aversive film memory.

METHODS

Sixty healthy students were subjected to the trauma film paradigm and randomly allocated to either: Tetris_dualtask, IR or no-intervention. Main outcomes were the number of film-related intrusions at one week and vividness and emotionality ratings of the most aversive film memory. Secondary outcomes were PTSD-like symptoms, intrusion intensity, and explicit film memory.

RESULTS

The Tetris_dualtask group reported significant fewer intrusions compared to the no-intervention group; whereas the IR group did not. No effect was found on vividness and emotionality ratings, PTSD-like symptoms, intrusion intensity, and explicit memory.

LIMITATIONS

The sample size was small, and analogue trauma in healthy individuals was examined, thus generalizability may be limited. Also, to increase comparability between interventions, the duration of Tetris_dualtask and IR was standardized. As a result, the IR intervention was shorter compared to other studies, which might have decreased its efficacy.

CONCLUSIONS

The results of this pilot study suggest that playing Tetris during retrieval of traumatic images, might hold potential as an early intervention strategy to reduce intrusions in the early aftermath of trauma and adversity. However, future large-scale replication research is needed.

Effects of a dissociative drug on fronto-limbic resting-state functional connectivity in individuals with posttraumatic stress disorder: a randomized controlled pilot study

RATIONALE

A subanesthetic dose of ketamine, a non-competitive N-methyl-D-aspartate glutamate receptor (NMDAR) antagonist, elicits dissociation in individuals with posttraumatic stress disorder (PTSD), who also often suffer from chronic dissociative symptoms in daily life. These debilitating symptoms have not only been linked to worse PTSD trajectories, but also to increased resting-state functional connectivity (RSFC) between medial prefrontal cortex (mPFC) and amygdala, supporting the conceptualization of dissociation as emotion overmodulation. Yet, as studies were observational, causal evidence is lacking.

OBJECTIVES

The present randomized controlled pilot study examines the effect of ketamine, a dissociative drug, on RSFC between mPFC subregions and amygdala in individuals with PTSD.

METHODS

Twenty-six individuals with PTSD received either ketamine (0.5mg/kg; n = 12) or the control drug midazolam (0.045mg/kg; n = 14) during functional magnetic resonance imaging (fMRI). RSFC between amygdala and mPFC subregions, i.e., ventromedial PFC (vmPFC), dorsomedial PFC (dmPFC) and anterior-medial PFC (amPFC), was assessed at baseline and during intravenous drug infusion.

RESULTS

Contrary to pre-registered predictions, ketamine did not promote a greater increase in RSFC between amygdala and mPFC subregions from baseline to infusion compared to midazolam. Instead, ketamine elicited a stronger transient decrease in vmPFC-amygdala RSFC compared to midazolam.

CONCLUSIONS

A dissociative drug did not increase fronto-limbic RSFC in individuals with PTSD. These preliminary experimental findings contrast with prior correlative findings and call for further exploration and, potentially, a more differentiated view on the neurobiological underpinning of dissociative phenomena in PTSD.

Challenging memories reduces intrusive memories and the memory amplification effect

This study scrutinizes the influence of attenuating beliefs about the veracity of traumatic experiences on the manifestation of intrusive recollections and the memory amplification effect. Participants were exposed to distress-inducing visual stimuli, subsequently rating their emotional status pre and post exposure. They engaged in a recognition task, identifying scenarios within the stimuli. Participants' recall was contested, casting doubt about the occurrence of certain scenes. Subsequently, they maintained a daily log of intrusive memories over a week. A second session reiterated the same process. This method effectively diminished the certainty in the participants' traumatic memories. Scenes whose occurrence was contested demonstrated a significant decline in both intrusive memories and memory amplification when juxtaposed with uncontested ones. Interestingly, no significant correlation emerged between the diminished belief in traumatic incidents and reductions in intrusive memory or memory amplification. Thus, this study advocates that interrogating the veracity of traumatic recollections can mitigate the prevalence of intrusive memories and the memory amplification effect, suggesting a novel potential therapeutic approach for trauma-related disorders.

The dilemma of trauma-focused therapy: effects of imagery rescripting on voluntary memory

Trauma-focused imagery-based interventions are suspected to alter or even distort declarative voluntary memory of a traumatic event, especially if they involve the active modification of imagery, e.g., as used in imagery rescripting (ImRs). However, systematic research is lacking so far. To investigate whether ImRs modifies voluntary memory of a standardized autobiographical aversive event (Trier Social Stress Test) (Session 1), healthy participants (N = 100) were randomly assigned to either an intervention condition receiving one session of ImRs or to a no-intervention control condition (NIC) (Session 2). Voluntary memory was examined using a free recall (Sessions 2 and 3) and a cued recall (Sessions 3 and 4). Although voluntary memory tended to deteriorate over time, contrary to expectations, this effect was not associated with ImRs. Remarkably, the number of correct details in free recall even improved in ImRs but not in NIC. This challenges the view that ImRs alters voluntary memory.

The relationship between tonic immobility and the development, severity, and course of posttraumatic stress disorder: Systematic and meta-analytic literature review

BACKGROUND

Tonic immobility (TI) is a reflexive, involuntary response that causes motor inhibition, vocal suppression, and analgesia. TI is elicited by extreme fear and perception of entrapment in a life-threatening situation. Research suggests that TI is a frequent peritraumatic response and may be related to subsequent posttraumatic stress disorder (PTSD). However, findings are mixed and, as of yet, no systematic or meta-analytic review examining associations between TI and PTSD has been published.

OBJECTIVE

We systematically and meta-analytically reviewed the literature and investigated whether TI is associated with the development, severity, and course of PTSD. Additionally, we evaluated whether different types of traumatic events are differentially associated with TI, and whether TI severity differs according to sex.

METHODS

A systematic literature search was conducted using Embase, PubMed, PsycINFO, and Scopus. Meta-analyses were performed on the included articles.

RESULTS

We identified 27 eligible articles. We found a significant association between TI and PTSD symptom severity (r = 0.39, 95% CI: 0.34-0.44; p < .0001). TI was more severe among females (Cohen's d=0.37, 95% CI: 0.25-0.48; p < .0001) and was more often elicited in situations involving interpersonal violence. We found limited longitudinal data to perform a meta-analysis of the association between TI and the development and/or course of PTSD. However, the literature available seems to support the role of TI in both the development and course of PTSD.

CONCLUSIONS

Peritraumatic TI is associated with PTSD symptom severity, occurs more often during interpersonal violence, and is more severe among females. More longitudinal research is needed to investigate the role of TI in psychopathology development and course.

Experimental induction of peritraumatic dissociation: The role of negative affect and pain and their psychophysiological and neural correlates

While research has elucidated processes underlying dissociative symptoms in patients with posttraumatic stress disorder, little is known about the circumstances under which trauma-related dissociation initially arises. To experimentally investigate causes and concomitants of peritraumatic dissociation, we subjected sixty-nine healthy women to aversive-audiovisual and painful-electrical stimulation in a 2(aversive/neutral film) x 2(pain/no pain) within-subject design while recording psychophysiological and fMRI-BOLD responses. Afterwards, participants rated negative-affect, pain, and dissociation for each condition. Using Bayesian multilevel regression models, we examined (1) whether aversive-audiovisual and painful-electrical stimulation elicit higher dissociation-levels than control conditions and (2) whether stronger negative-affect and pain responses (operationalized via self-report, psychophysiological, and neural markers) correlate with higher dissociation-levels. Several key findings emerged: Both aversive-audiovisual and painful-electrical stimulation elicited dissociation. Dissociation was linked to higher self-reported negative-affect, but we did not find enough evidence linking it to psychophysiological and neural negative-affect markers. However, dissociation was associated with higher levels of self-reported pain, a skin-conductance-response-based pain marker, and the fMRI-BOLD-based Neurologic-Pain-Signature. Results indicate that both aversive-audiovisual and painful stimuli can independently cause dissociation. Critically, pain responses captured via self-report, psychophysiological, and neural markers were consistently linked to higher dissociation-levels suggesting a specific, evolutionary meaningful, contribution of pain to the rise of dissociation.

Neuroscientific evidence for pain being a classically conditioned response to trauma- and pain-related cues in humans

ABSTRACT

Psychological trauma is typically accompanied by physical pain, and posttraumatic stress disorder (PTSD) often co-occurs with chronic pain. Clinical reports suggest that pain after trauma may be part of a re-experiencing symptomatology. Classical conditioning can underlie visual re-experiencing since intrusions can occur as conditioned responses (CRs) to trauma-related cues. If individuals also experience pain to cues previously paired with, but not anymore inflicting nociceptive stimulation (CSs), conditioning could also explain re-experiencing of pain. Sixty-five participants underwent classical conditioning, where painful electrocutaneous stimulation and aversive film-clips served as unconditioned stimuli (USs) in a 2(pain/no pain)×2(aversive/neutral film) design. CSs were neutral pictures depicting contextual details from the films. One day later, participants were re-exposed to CSs during a memory-triggering-task (MTT). We assessed pain-CRs by self-report and an fMRI-based marker of nociceptive pain, the neurologic pain signature (NPS); and recorded spontaneous daily-life pain-intrusions with an e-diary. During conditioning, pain-signaling CSs elicited more self-reported-pain and NPS-responses than no-pain-signaling CSs. Possibly because the aversive-film masked differences in participants' responses to pain-signaling vs. no-pain-signaling CSs, pain-CRs during acquisition only emerged within the neutral-film condition. When participants were re-exposed to CSs during MTT, self-reported-pain-CRs during the neutral-film condition and, though more uncertain, NPS-CRs during the aversive-film condition persisted. Importantly, participants with stronger pain-CRs showed a greater probability and severity of experiencing spontaneous pain intrusions during daily-life. Our data support that pain can emerge as a CR with emotional and sensory components. Classical conditioning presents a possible mechanism explaining pain-intrusions, and more broadly, pain experienced without nociceptive input.

Investigating the frequency of intrusive memories after 24 hours using a visuospatial interference intervention: a follow-up and extension

BACKGROUND

There is a need for effective, low-cost, readily available measures for reducing trauma symptoms so that people exposed to potentially traumatic events can receive help more quickly. A previous study reported that performing an intervention including a visuospatial task shortly after a reminder of a series of unpleasant film clips seen 24 hours earlier reduced the number of intrusive memories over the following week.

OBJECTIVE

This study reports a follow-up and extension of the earlier promising finding. The prediction was that participants performing the visuospatial task immediately after the reminder would report fewer intrusions compared to three other groups who 1) performed no task, and novel conditions who 2) performed the task before the reminder, and 3) performed the task 90 minutes after the reminder.

METHOD

A trauma-analogue method was used, where students (N = 200) watched a series of short films with unpleasant material. Over the following week, they were asked to write down any intrusive memories they experienced in a diary. On the second day they returned to the lab and saw static reminders of the films. They were then randomly allocated to condition, recorded intrusive memories over the following days and returned to the lab for final testing on Day 8.

RESULTS

A total of 49 participants did not report any intrusions and were excluded from the analyses. Two more participants were excluded as outliers, leaving a final sample of n = 149. Despite using largely the same materials as the original study there were no significant differences in the number of intrusive memories between the four groups post intervention.

CONCLUSIONS

Possible explanations include the effect not being as robust as expected, a low number of intrusions across groups, baseline differences in attention, and minor but potentially important differences in procedure between this and the original study.

Peritraumatic dissociation revisited: associations with autonomic activation, facial movements, staring, and intrusion formation

BACKGROUND

Peritraumatic dissociation is purported to emerge together with attenuated autonomic arousal, immobility, and staring. However, empirical evidence is scarce and heterogeneous. Moreover, it is still a matter of debate whether these responses predict intrusion formation.

OBJECTIVE

The present trauma-analogue study examined associations between peritraumatic dissociation, autonomic activation, facial movements, staring, and intrusion formation.

METHOD

Seventy-one healthy women watched a highly aversive film, while autonomic activation (heart rate, respiratory sinus arrhythmia, skin conductance level), facial movements (temporal variations in corrugator electromyography), and staring (fixation duration, tracklength) were assessed. Afterwards, participants rated the intensity of dissociation during film viewing and reported intrusions and associated distress in a smartphone application for 24 hours.

RESULTS

Peritraumatic dissociation was linked to higher autonomic arousal (higher heart rate and, on a trend-level, lower respiratory sinus arrhythmia), increased facial movements, and staring (lower tracklength). Peritraumatic dissociation, higher autonomic arousal (higher heart rate and lower respiratory sinus arrhythmia), staring (higher fixation duration), and, on a trend-level, more facial movements were linked to higher intrusion load (number x distress of intrusions) and together explained 59% of variance. Skin conductance level was neither linked to peritraumatic dissociation nor intrusion load.

CONCLUSIONS

Our results suggest that, at low-dissociation-levels observed in trauma-analogue studies, peritraumatic dissociation may occur together with heightened autonomic arousal and facial movements, indexing increased negative affect. Staring might, irrespectively of dissociation-levels, serve as objective marker for dissociation. Together, peritraumatic dissociation and its psychophysiological correlates might set the stage for later intrusion formation.

Freeze-like responses to pain in humans and its modulation by social context

Background

Maladaptive defensive responses such as excessive avoidance behavior have received increasing attention as a main mechanism for the development and maintenance of chronic pain complaints. However, another defensive response which is commonly studied in animals as a proxy for fear is freezing behavior. No research to date has investigated human freezing behavior in the context of pain. In addition, there is an increasing realization that social context can affect pain-relevant processes such as pain experience and pain behavior but less is known about the effects of social context on defensive responses to pain. Hence, this study investigated freezing behavior and facial pain expression in the context of pain, and their modulation by social context.

Methods

Healthy, pain-free participants (N = 39) stood on a stabilometric force platform in a threatening or safe social context, which was manipulated using angry or happy facial stimuli. In some trials, an auditory cue (conditioned stimulus; CS) predicted the occurrence of painful electrocutaneous stimulus (unconditioned stimulus; pain-US). We assessed body sway (an index of freezing), heart rate, facial pain expression, self-reported pain intensity, unpleasantness, and pain-US expectancy during the CS and the context alone (no CS).

Results

The results were mixed. Neither the anticipation of pain, nor social context affected body sway. Heart rate and painful facial expression were reduced in the threatening social context at high anxiety levels. A threatening social context also elicited higher pain-US expectancy ratings. In sum, a threatening social context increases the expectation of pain, but reduces the facial expression of pain and lowers heart rate in highly anxious individuals.

Rescripting experimental trauma: Effects of imagery and writing as a way to reduce the development of intrusive memories

BACKGROUND AND OBJECTIVES

Imagery rescripting is an effective treatment strategy for trauma related disorders, but its underlying mechanisms are still largely unknown. The aim of the present study was to test whether a) imagery (versus writing) is essential in the process of rescripting, and b) rescripting affects emotional memories on an implicit level.

METHODS

Healthy participants were subjected to an experimental trauma ('trauma film'), and randomly allocated to four conditions: recall of film + Imagery Rescripting (ImRs), recall of film + Writing Rescripting (WRs), recall only (ImRE), or no recall + no manipulation (NM). Next, participants recorded intrusion frequency and distress during one week, after which they executed a visual interference task (VIT) including neutral and trauma film stills, to access implicit emotional memory.

RESULTS

Main findings were that ImRs and WRs resulted in fewer intrusions than NM, with no differences between both rescripting conditions. We did not find an effect on intrusion distress and the VIT.

LIMITATIONS

Stills in the VIT were distracted from all four film scenes, whereas rescripting was done on one scene only, possibly obscuring the effect. Also, an analogue sample was used, which may limit generalizability to clinical samples.

CONCLUSIONS

We replicated previous effects of ImRs on intrusion development. Furthermore, no superior effect of imagery as key modality for rescripting was found; writing seems a viable alternative. Measures for implicit emotional memory such as the VIT may have to be applied relatively soon after the experimental session (e.g., same day as the experimental session).

Tonic immobility predicts poorer recovery from posttraumatic stress disorder

BACKGROUND

Tonic immobility (TI; a state of motor arrest during threat) and has been found to be associated with the development of psychopathology. It also hindered recovery from posttraumatic stress disorder (PTSD) after pharmacological treatment. The present study investigated the role of TI in recovery from PTSD in a large representative community sample with mixed traumas outside an exclusive treatment context.

METHODS

Participants with PTSD from the panel for Longitudinal Internet Studies for the Social Sciences (LISS) completed measures for trauma, PTSD symptoms, and peritraumatic responses (fear, dissociation, and TI) in two subsequent years. Traumatized participants with PTSD were selected for the analyses (N = 262).

RESULTS

TI was a relevant predictor for increased PTSD symptoms in year 2 after controlling for peritraumatic fear, peritraumatic dissociation, and PTSD symptoms in year 1, especially in abuse victims. Peritraumatic fear and dissociation no longer predicted PTSD in year 2 after entering TI in the model.

CONCLUSIONS

Our results indicate that TI may indeed hinder recovery from PTSD. TI may thus be a relevant factor to take into account after trauma and in treatment. The effects of TI may be especially negative for abuse victims.

The effects of dual-tasks on intrusive memories following analogue trauma

Patients with post-traumatic stress disorder frequently and involuntarily experience intrusions, which are strongly linked to the trauma hotspot. Voluntary memory characteristics (i.e., vividness and unpleasantness) of this hotspot can be reduced by performing a dual-task, such as making horizontal eye movements, which is frequently used in Eye Movement Desensitization and Reprocessing. We tested whether such dual-task interventions would also reduce involuntary memory (i.e., intrusions). Moreover, we examined if changes in hotspot vividness and unpleasantness predicted intrusion frequency. Additionally, we examined whether the effects were dependent on dual-task modality. We tested this in three experiments. Participants watched a trauma film and performed one of the interventions 10-min post-film (1) Recall + Eye movements, (2) Recall + Counting, or (3) No-Task Control. Before and after the intervention, participants rated the hotspot vividness and unpleasantness. They recorded intrusive memories about the film in a diary for a week. Unexpectedly, we found that hotspot vividness and unpleasantness ratings were not affected by the intervention. However, the prolonged (experiment 2), but not standard (experiment 1), dual-task interventions resulted in a lower number of intrusions, regardless of modality. However, this effect was not replicated in experiment 3. We discuss potential explanations and present suggestions for future research.

Evidence for subjective emotional numbing following induced acute dissociation

The aim of the study was to examine the effects of acute dissociation on emotional responsivity in healthy individuals. We used a previously validated technique (mirror-gazing, Caputo, 2010) to experimentally induce acute dissociation in non-clinical participants and assessed post-induction subjective responsivity (ratings of valence and arousal) to standardized emotional images. Fifty non-clinical participants were randomised to either the dissociation induction (n = 25) or control conditions (n = 25). The dissociation manipulation effect was corroborated by a significant post-induction elevation in state dissociation in the dissociation-induction group relative to controls (p = .004). The dissociation-induction group rated negative (p = .028) and neutral (p = .025) stimuli as significantly less unpleasant than controls. There was also a non-significant trend for positive stimuli to be rated as less pleasant by the dissociation-induction group compared to controls (p = .060). These findings provide experimental evidence for the short-term alleviation (i.e., emotional numbing) of negative affect during dissociative states, which may serve as a coping mechanism for some individuals. However, this tendency of emotional numbing also reduced positive affective responses to pleasant stimuli to some extent. Further investigation of dissociative phenomena and their impact on emotional processing appears warranted.

The role of tonic immobility and control in the development of intrusive memories after experimental trauma

Tonic immobility (TI; state of motor inhibition during threat) has been implicated in the onset of intrusive trauma memories, while controllability was associated with reduced anxiety. The present study investigated the interaction between TI and control in the development of intrusive memories of an analogue trauma. Sixty-four participants watched negative pictures while being allowed to close their eyes (InControl) or not (NoControl). They completed measures for spontaneous TI afterwards and recorded intrusive memories of the pictures in a diary in the subsequent week. Bayesian analyses were used to test informative hypotheses. Spontaneous TI during picture viewing was positively associated with increased intrusion frequency. Intrusion frequency did not differ for InControl versus NoControl. Moderation (control x TI) and non-moderation (main effect of TI only) were both adequate models, with no preference. Our results confirm the importance of TI in PTSD development. Implications of the findings regarding control merit more research.

Tonic immobility during re-experiencing the traumatic event in posttraumatic stress disorder

Tonic Immobility (TI) is an evolved defence response, characterized by physical immobility. Peritraumatic TI has been linked to posttraumatic stress disorder (PTSD). However, samples sizes in clinical studies have been small, and little is known about TI reactions post trauma, for instance during trauma reminders. The prevalence of peritraumatic TI and TI during re-experiencing the traumatic event was examined by self-report in 184 patients with chronic PTSD. Moderate peritraumatic TI was reported by 26.6% of the participants (n = 49) and extreme peritraumatic TI by 52.2% (n = 96). During re-experiencing the traumatic event, 35.3% (n = 65) reported moderate TI, and 37.0% (n = 68) extreme TI. Peritraumatic TI was related to PTSD symptom severity and TI during re-experiencing mediated this relationship. In line with previous findings, reports of peritraumatic TI were high among PTSD patients. In addition, we showed that it often re-occurred during re-experiencing the traumatic event. The prevalence of TI at different stages post trauma warrants future study.

Visuospatial context learning and configuration learning is associated with analogue traumatic intrusions

BACKGROUND AND OBJECTIVES

Cognitive and information processing theories of Post-Traumatic Stress Disorder (PTSD) assert that trauma intrusions are characterized by poor contextual embedding of visuospatial memories. Therefore, efficient encoding of visuospatial contextual information might protect against intrusions. We tested this idea using indices of visuospatial memory embedding along with the trauma film paradigm.

METHODS

Individual differences in spatial configuration learning, as well as the degree to which visual recognition memory depends on its visual encoding context (i.e., memory contextualization), were assessed in 81 healthy participants. Next, participants viewed a distressing film. Intrusions and other PTSD analogue symptoms were assessed subsequently.

RESULTS

Participants displaying stronger memory contextualization developed fewer intrusions and PTSD analogue symptoms. Spatial configuration learning was unrelated to memory contextualization and, contrary to prior findings, predicted higher levels of intrusions.

LIMITATIONS

Due to the analogue design, our findings may not translate directly to clinical populations. Furthermore, due to the correlational design of the study, causal relations remain to be tested.

CONCLUSIONS

Our results suggest a protective role for the ability to integrate memories in their original visual learning context against the development of PTSD symptoms.

Tetris and Word games lead to fewer intrusive memories when applied several days after analogue trauma

Background: Intrusive trauma memories are a key symptom of posttraumatic stress disorder (PTSD), so disrupting their recurrence is highly important. Intrusion development was hindered by visuospatial interventions administered up to 24 hours after analogue trauma. It is unknown whether interventions can be applied later, and whether modality or working-memory load are crucial factors. Objectives: This study tested: (1) whether a visuospatial task would lead to fewer intrusions compared to a reactivation-only group when applied after memory reactivation four days after analogue trauma exposure (extended replication), (2) whether both tasks (i.e. one aimed to be visuospatial, one more verbal) would lead to fewer intrusions than the reactivation-only group (intervention effect), and (3) whether supposed task modality (visuospatial or verbal) is a critical component (modality effect). Method: Fifty-four participants were randomly assigned to reactivation+Tetris (visuospatial), reactivation+Word games (verbal), or reactivation-only (no task). They watched an aversive film (day 0) and recorded intrusive memories of the film in diary A. On day 4, memory was reactivated, after which participants played Tetris, Word games, or had no task for 10 minutes. They then kept a second diary (B). Informative hypotheses were evaluated using Bayes factors. Results: Reactivation+Tetris and reactivation+Word games resulted in relatively fewer intrusions from the last day of diary A to the first day of diary B than reactivation-only (objective 1 and 2). Thus, both tasks were effective even when applied days after analogue trauma. Reactivation-only was not effective. Reactivation+Word games appeared to result in fewer intrusions than reactivation+Tetris (objective 3; modality effect), but this evidence was weak. Explorative analyses showed that Word games were more difficult than Tetris. Conclusions: Applying a task four days after the trauma film (during memory reconsolidation) was effective. The modality versus working-memory load issue is inconclusive.

The relationship between suppression and subsequent intrusions: the mediating role of peritraumatic dissociation and anxiety

BACKGROUND AND OBJECTIVES

Although previous studies showed that thought and emotion suppression represent risk factors for intrusions development, the mechanisms that explain these relations were less explored. This study aims to examine the relationships between thought and emotion suppression and the symptoms of intrusion following the exposure to a trauma-related event. Moreover, we explored if these relationships would be mediated by peritraumatic state dissociation and state anxiety.

DESIGN AND METHODS

The trauma film paradigm was used and the participants were students (N = 148) experimentally exposed to an aversive film to model a traumatic experience. Thought and emotion suppression were measured before the trauma exposure. After exposure, the participants completed scales for measuring state dissociation and state anxiety. Intrusive images and thoughts of the film were recorded in the subsequent week using an intrusion diary.

RESULTS

Thought suppression predicted intrusive thoughts frequency, and this effect was mediated by the peritraumatic anxiety. State anxiety predicted both intrusive images and thoughts, while state dissociation only predicted intrusive images.

CONCLUSIONS

Intrusive images and intrusive thoughts are different phenomena and they are predicted by different variables. The practical implications of these results for posttraumatic stress disorder treatment and secondary traumatization are discussed.

Tonic immobility differentiates stress responses in PTSD

BACKGROUND

Tonic immobility (TI) is a state of physical immobility associated with extreme stress and the development of posttraumatic stress disorder (PTSD). However, it is unknown whether TI is associated with a distinct actual stress response, i.e., objective immobility measured by a stabilometric platform. This study made a first step in exploring this as well as differences in body sway responses between PTSD patients and healthy controls. We hypothesized that PTSD would be related to increased body sway under stress, whereas TI would be related to decreased body sway under stress.

METHODS

Eye closure was selected as a PTSD-relevant stress induction procedure. Body sway and heart rate (HR) were measured in 12 PTSD patients and 12 healthy controls in four conditions: (1) maintaining a stable stance with eyes open, (2) with eyes closed, (3) during a mental arithmetic task with eyes open, and (4) with eyes closed.

RESULTS

As predicted, PTSD patients showed increased body sway from eyes open to eyes closed compared to controls and this effect was eliminated by executing the arithmetic task. Most importantly, retrospective self-reported TI was associated with lower body sway increases in PTSD and higher body sway decreases in controls from eyes-open to eyes-closed conditions.

CONCLUSIONS

These preliminary findings suggest that eye closure has a different effect on PTSD patients than controls and that high self-reported TI might indicate a distinct stress response pattern, i.e., a proneness for immobility. It may be relevant to take such individual differences in stress-response into account in PTSD treatment.

Dysfunctional Freezing Responses to Approaching Stimuli in Persons with a Looming Cognitive Style for Physical Threats

Immobilizing freezing responses are associated with anxiety and may be etiologically related to several anxiety disorders. Although recent studies have sought to investigate the underlying mechanisms in freezing responses that are so problematic in many forms of anxiety, cognitive factors related to anxiety have not been investigated. This study was designed to investigate the potential moderating role of a well-documented cognitive vulnerability to anxiety, the Looming Cognitive Style (i.e., LCS; Riskind et al., 2000), which assesses the extent to which individuals tend to routinely interpret ambiguous threats (e.g., physical or social threats) in a biased manner as approaching. We assessed participants' Reaction Times (RTs) when they made judgments about images of animals that differed in threat valence (threat or neutral) and motion direction (approach or recede). As expected, LCS for concerns about the approach of physical dangers appeared to moderate freeze reactions. Individuals who were high on this LCS factor tended to generally exhibit a freeze-response (slower RTs) and this was independent of the threat valence or motion direction of the animals. These general freezing reactions were in stark contrast to those of individuals who were low on the LCS factor for concerns about the approach of physical dangers. These participants tended to exhibit more selective and functional freezing responses that occurred only to threatening animals with approach motion; they did not exhibit freezing to neutral stimuli or any stimuli with receding motion. These findings did not appear to be explicable by a general slowing of RTs for the participants with high LCS. Moreover, the LCS factor for concerns about social threats (such as rejection or embarrassment) was not related to differences in freezing; there was also no additional relationship of freezing to behavioral inhibition scores on the Behavioral Inhibition System and the Behavioral Activation System Scales (BIS/BAS). It may prove fruitful to further explore cognitive factors related to anxiety to develop a more comprehensive understanding of how these factors are associated with anxiety-related freezing responses.

Vantage perspective during encoding: The effects on phenomenological memory characteristics

The vantage perspective from which a memory is retrieved influences the memory's emotional impact, intrusiveness, and phenomenological characteristics. This study tested whether similar effects are observed when participants were instructed to imagine the events from a specific perspective. Fifty student participants listened to a verbal report of car-accidents and visualized the scenery from either a field or observer perspective. There were no between-condition differences in emotionality of memories and the number of intrusions, but imagery experienced from a relative observer perspective was rated as less self-relevant. In contrast to earlier studies on memory retrieval, vantage perspective influenced phenomenological memory characteristics of the memory representation such as sensory details, and ratings of vividness and distancing of the memory. However, vantage perspective is most likely not a stable phenomenological characteristic itself. Implications and suggestions for future research are discussed.

Attention and postural control in patients with conversion paresis

OBJECTIVE

Current theories of conversion disorder (CD) propose that motor symptoms are related to heightened self-monitoring and excessive cognitive control of movements. We tested this hypothesis using quantification of performance on a continuous perceptuo-motor task involving quiet standing.

METHODS

Twelve CD patients and matched controls maintained static balance on a force platform under various attention conditions: (1) with eyes open; (2) with eyes closed (requiring enhanced attention to proprioceptive information to regulate posture); and (3) while performing an attention demanding cognitive task.

RESULTS

Compared to controls, CD patients displayed a greater decrease in postural stability in the 'eyes-closed' versus 'eyes-open' condition. In contrast, cognitive distraction led to a normalization of balance in CD. Moreover, sensitivity to the balance interventions correlated significantly with trauma reports and dissociative symptoms.

CONCLUSION

These results indicate that attention plays a crucial role in postural control in CD. More specifically, patients seem to inadvertently use deliberate control of posture (i.e., cognitive investment) of an otherwise nearly automatized perceptuo-motor task. Attentional distraction resulted in a temporary normalization of balance, which may be used to train individuals with CD to guide their attention in a more effective way.

Mental Imagery Affects Subsequent Automatic Defense Responses

Automatic defense responses promote survival and appropriate action under threat. They have also been associated with the development of threat-related psychiatric syndromes. Targeting such automatic responses during threat may be useful in populations with frequent threat exposure. Here, two experiments explored whether mental imagery as a pre-trauma manipulation could influence fear bradycardia (a core characteristic of freezing) during subsequent analog trauma (affective picture viewing). Image-based interventions have proven successful in the treatment of threat-related disorders and are easily applicable. In Experiment 1, 43 healthy participants were randomly assigned to an imagery script condition. Participants executed a passive viewing task with blocks of neutral, pleasant, and unpleasant pictures after listening to an auditory script that was either related (with a positive or a negative outcome) or unrelated to the unpleasant pictures from the passive viewing task. Heart rate was assessed during script listening and during passive viewing. Imagining negative related scripts resulted in greater bradycardia (neutral-unpleasant contrast) than imagining positive scripts, especially unrelated. This effect was replicated in Experiment 2 (n = 51), again in the neutral-unpleasant contrast. An extra no-script condition showed that bradycardia was not induced by the negative-related script, but rather that a positive script attenuated bradycardia. These preliminary results might indicate reduced vigilance after unrelated positive events. Future research should replicate these findings using a larger sample. Either way, the findings show that highly automatic defense behavior can be influenced by relatively simple mental imagery manipulations.

Cultural differences in the relationship between intrusions and trauma narratives using the trauma film paradigm

Two studies explored the influence of culture on the relationship between British and East Asian adults’ autobiographical remembering of trauma film material and associated intrusions. Participants were shown aversive film clips to elicit intrusive images. Then participants provided a post-film narrative of the film content (only Study 1). In both studies, participants reported intrusive images for the film in an intrusion diary during the week after viewing. On returning the diary, participants provided a narrative of the film (delayed). The trauma film narratives were scored for memory-content variables. It was found that for British participants, higher levels of autonomous orientation (i.e. expressions of autonomy and self-determination) and self-focus in the delayed narratives were correlated significantly with fewer intrusions. For the East Asian group, lower levels of autonomous orientation and greater focus on others were correlated significantly with fewer intrusions. Additionally, Study 2 found that by removing the post-film narrative task there was a significant increase in the number of intrusions relative to Study 1, suggesting that the opportunity to develop a narrative resulted in fewer intrusions. These findings suggest that the greater the integration and contextualization of the trauma memory, and the more the trauma memory reflects culturally appropriate remembering, the fewer the intrusions.

First steps in using machine learning on fMRI data to predict intrusive memories of traumatic film footage

After psychological trauma, why do some only some parts of the traumatic event return as intrusive memories while others do not? Intrusive memories are key to cognitive behavioural treatment for post-traumatic stress disorder, and an aetiological understanding is warranted. We present here analyses using multivariate pattern analysis (MVPA) and a machine learning classifier to investigate whether peri-traumatic brain activation was able to predict later intrusive memories (i.e. before they had happened). To provide a methodological basis for understanding the context of the current results, we first show how functional magnetic resonance imaging (fMRI) during an experimental analogue of trauma (a trauma film) via a prospective event-related design was able to capture an individual's later intrusive memories. Results showed widespread increases in brain activation at encoding when viewing a scene in the scanner that would later return as an intrusive memory in the real world. These fMRI results were replicated in a second study. While traditional mass univariate regression analysis highlighted an association between brain processing and symptomatology, this is not the same as prediction. Using MVPA and a machine learning classifier, it was possible to predict later intrusive memories across participants with 68% accuracy, and within a participant with 97% accuracy; i.e. the classifier could identify out of multiple scenes those that would later return as an intrusive memory. We also report here brain networks key in intrusive memory prediction. MVPA opens the possibility of decoding brain activity to reconstruct idiosyncratic cognitive events with relevance to understanding and predicting mental health symptoms.

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Why only some moments within a trauma intrude while others do not is unclear.

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Neuroimaging may provide further clues as to why this is the case.

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Multivariate pattern analysis, a recent neuroimaging analysis tool, was able to predict intrusive memories.

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Those brain networks involved in intrusive memory prediction are presented.

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Multivariate pattern analysis may inform future innovation in mental health.

Low emotional response to traumatic footage is associated with an absence of analogue flashbacks: an individual participant data meta-analysis of 16 trauma film paradigm experiments

Most people will experience or witness a traumatic event. A common occurrence after trauma is the experience of involuntary emotional memories of the traumatic event, herewith “flashbacks”. Some individuals, however, report no flashbacks. Prospective work investigating psychological factors associated with an absence of flashbacks is lacking. We performed an individual participant data meta-analysis on 16 experiments (n = 458) using the trauma film paradigm to investigate the association of emotional response to traumatic film footage and commonly collected baseline characteristics (trait anxiety, current depression, trauma history) with an absence of analogue flashbacks. An absence of analogue flashbacks was associated with low emotional response to the traumatic film footage and, to a lesser extent, low trait anxiety and low current depression levels. Trauma history and recognition memory for the film were not significantly associated with an absence of analogue flashbacks. Understanding why some individuals report an absence of flashbacks may aid preventative treatments against flashback development.

Human freezing in response to affective films

Human freezing has been objectively assessed using a passive picture viewing paradigm as an analog for threat. These results should be replicated for other stimuli in order to determine their stability and generalizability. Affective films are used frequently to elicit affective responses, but it is unknown whether they also elicit freezing-like defense responses. To test whether this is the case, 50 participants watched neutral, pleasant and unpleasant film fragments while standing on a stabilometric platform and wearing a polar band to assess heart rate. Freezing-like responses (indicated by overall reduced body sway and heart rate deceleration) were observed for the unpleasant film only. The unpleasant film also elicited early reduced body sway (1-2 s after stimulus onset). Heart rate and body sway were correlated during the unpleasant film only. The results suggest that ecologically valid stimuli like films are adequate stimuli in evoking defense responses. The results also underscore the importance of including time courses in human experimental research on defense reactions in order to delineate different stages in the defense response.

Contextual representations increase analogue traumatic intrusions: evidence against a dual-representation account of peri-traumatic processing

BACKGROUND AND OBJECTIVES

Information processing accounts of post-traumatic stress disorder (PTSD) state that intrusive memories emerge due to a lack of integration between perceptual and contextual trauma representations in autobiographical memory. This hypothesis was tested experimentally using an analogue trauma paradigm in which participants viewed an aversive film designed to elicit involuntary recollections.

METHOD

Participants viewed scenes from the film either paired with contextual information or with the contextual information omitted. After viewing the film participants were asked to record for one week any involuntary intrusions for the film using a provided intrusions diary.

RESULTS

The results revealed a significant increase in analogue intrusions for the film when viewed with contextual information in comparison to when the film was viewed with the contextual information omitted. In contrast there was no effect of contextual information on valence ratings or voluntary memory for the film, or on the reported vividness and emotionality of the intrusions.

LIMITATIONS

The analogue trauma paradigm may have failed to reproduce the effect of extreme stress on encoding that is postulated to occur during PTSD.

CONCLUSIONS

The findings have potential implications for trauma intervention as they suggest that the contextual understanding of a scene during encoding can be integral to the subsequent occurrence of traumatic intrusions. The pattern of results found in the study are inconsistent with dual-representation accounts of intrusive memory formation, and instead provide new evidence that contextual representations play a casual role in increasing the frequency of involuntary intrusions for traumatic material.

The prediction of intrusions following an analogue traumatic event: peritraumatic cognitive processes and anxiety-focused rumination versus rumination in response to intrusions

Intrusions are often considered the hallmark of posttraumatic stress disorder (PTSD). Despite this, relatively little is known about factors that give rise to intrusions. Cognitive models of PTSD highlight the importance of pre-existing cognitive vulnerabilities, cognitive processing and anxiety during a traumatic event, as well as negative responses to trauma sequelae. However, few studies have examined multiple forms of peritraumatic processes, and rumination in response to trauma intrusions using analogue trauma tasks, and none have examined whether broader anxious ruminative processes contribute to intrusion development. In addition, little work has investigated the role of post-state anxiety in intrusions, and anxiety may be related to both peritraumatic processing and rumination. The current study employed a distressing film paradigm to examine key tenets of cognitive models of PTSD. Ninety-one female university students completed measures of anxiety, rumination in response to anxious symptoms, peritraumatic dissociation, data driven processing, lack of self referent processing, intrusions, and rumination in response to intrusions of the distressing film. Results revealed that peritraumatic dissociation, data driven processing, and self referent processing were associated with intrusion development, with lack of self referent processing being a strong predictor of intrusion development. Post-state anxiety and rumination in response to intrusions also predicted intrusion development. Discussion focuses on implications of cognitive processes and anxiety in theories of intrusion development.

Risk recognition and sensation seeking in revictimization and posttraumatic stress disorder

Impaired risk recognition has been suggested to be associated with the risk for revictimization and the development of posttraumatic stress disorder (PTSD). Moreover, risk behavior has been linked to high sensation seeking, which may also increase the probability of revictimization. A newly designed behavioral experiment with five audiotaped risk scenarios was used to investigate risk recognition in revictimized, single-victimized, and nontraumatized individuals with and without PTSD. Moreover, the potential role of sensation seeking in revictimization, and PTSD as well as its relation to risk recognition was explored. Revictimized, single-victimized, and nontraumatized individuals did not differ with regard to general risk recognition. However, delayed risk recognition was found for the revictimized group when arousal ratings were considered. No differences in sensation seeking were found between the three groups; only the nontraumatized group showed lower boredom susceptibility relative to the revictimized group. Delayed risk recognition was associated with high sensation seeking. Furthermore, PTSD symptoms significantly predicted exit levels of risk scenarios. Findings are discussed against the background of previous research.

Reduced intrusion development after post-trauma imagery rescripting; an experimental study

BACKGROUND AND OBJECTIVES

Contemporary theories predict PTSD development after trauma if trauma information is not adequately processed or negatively appraised. Mental imagery and emotional processing seem to be strongly related and evidence-based treatment strategies such as imaginal exposure and EMDR indeed include imagery as a main component. Moreover, imagery rescripting of traumatic memories is an effective treatment for PTSD.

METHODS

The present study combined these lines of research and investigated the impact of early imagery rescripting on intrusion development after an aversive film. Seventy-six participants were randomly allocated to one of three conditions: imagery rescripting (IRS), imagery reexperiencing (IRE) and positive imagery (PI). All participants watched an aversive film, had a 30-min break and then received a 9-min intervention (IRS, IRE or PI). They indicated subjective distress during the intervention, recorded intrusive memories of the film for 1 week and completed the Posttraumatic Cognitions Inventory (PTCI) and a cued recall test one week later.

RESULTS

The IRS group developed fewer intrusive memories relative to the IRE and PI groups, and less negative cognitions than the IRE group, while cued recall was enhanced in IRS and IRE groups compared to the PI group. IRS and PI groups experienced less distress during the intervention than the IRE group.

LIMITATIONS

This is an analogue design and results should be replicated in clinical samples.

CONCLUSIONS

The results suggest that IRS might be an adequate technique to change memory consolidation at an early stage and therefore a powerful and non-distressing strategy to prevent PTSD symptoms.

Attentional control affects the relationship between tonic immobility and intrusive memories

BACKGROUND AND OBJECTIVES

Cognitive control and tonic immobility (TI) have both been implicated in the development of PTSD, but it is not known how these factors are related. The present study investigated if a specific form of cognitive control (attentional control) would moderate the relationship between TI and intrusive memories.

METHODS

Participants (N = 43) completed the Attentional Control Scale (ACS) before watching an aversive film. They completed the Tonic Immobility Scale (TIS, with an immobility and fear subscale: TIS-TI and TIS-Fear) afterwards and recorded intrusive memories of the film in the subsequent week.

RESULTS

TIS-TI was related to intrusion frequency, while ACS was not. However, ACS had a moderating role; the relationship between TIS-TI and intrusion frequency was significant in low ACS but not in high ACS participants. The TIS-Fear subscale was not related to intrusion frequency in low ACS or high ACS participants.

LIMITATIONS

Replication of the results is merited in selected extreme groups and males.

CONCLUSIONS

The results may imply that enhanced attentional control serves as a protective factor against the development of intrusive memories after trauma.

Attention to the body in nonclinical somatoform dissociation depends on emotional state

OBJECTIVE

Unexplained neurological symptoms ("somatoform dissociation") are common in health care settings and associated with disproportionately high levels of distress, disability, and resource utilization. Theory suggests that somatoform dissociation is associated with disturbed attentional processing, but there is a paucity of research in this area and the available evidence is contradictory.

METHODS

We compared undergraduate participants (n=124) with high and low scores on the Somatoform Dissociation Questionnaire (SDQ-20) on a tactile cueing paradigm measuring the time course of attention to touch, following either a neutral film or a film designed to simulate the emotional effects of trauma exposure.

RESULTS

Following the neutral film, high SDQ-20 participants exhibited delayed disengagement from tactile cue stimuli compared to the low SDQ-20 group. Following the "trauma" film, however, the high SDQ-20 group showed attentional effects suggesting avoidance of the tactile stimuli in this condition. Early attention to tactile cues following the trauma film predicted film-related intrusive thoughts after the experiment.

CONCLUSION

These findings suggest that both body vigilance and body avoidance may be involved in the expression of somatoform dissociation.

Is it mere distraction? Peri-traumatic verbal tasks can increase analogue flashbacks but reduce voluntary memory performance

Several experiments have shown that we can reduce the frequency of analogue flashbacks with competing tasks presented during a trauma film (i.e. peri-traumatically). A "distraction" hypothesis suggests that any competing task may reduce flashbacks due to distraction and/or a load on executive control. Alternatively, a "modality" hypothesis based on clinical models of PTSD suggests that certain tasks will not protect against intrusions (Experiment 1) and could actually increase them (Experiment 2). Experiment 1 contrasted two concurrent tasks, Verbal Interference (counting backwards in threes) and Visuospatial tapping, against a no-task Control condition during trauma film viewing. The Visuospatial group had significantly fewer intrusions of the film over 1-week than the Control group. Contrary to a distraction account, the Verbal Interference group did not show this effect. Using a larger sample, Experiment 2 showed that the Verbal Interference group (counting backwards in sevens) had more intrusions (and inferior voluntary memory) than no-task Controls. We propose that this is in line with a modality hypothesis concerning trauma flashbacks. Disrupting verbal/conceptual processing during trauma could be harmful for later flashbacks.

Inducing and modulating intrusive emotional memories: a review of the trauma film paradigm

Highly affect-laden memory intrusions are a feature of several psychological disorders with intrusive images of trauma especially associated with post-traumatic stress disorder (PTSD). The trauma film paradigm provides a prospective experimental tool for investigating analogue peri-traumatic cognitive mechanisms underlying intrusion development. We review several historical papers and some more recent key studies that have used the trauma film paradigm. A heuristic diagram is presented, designed to simplify predictions about analogue peri-traumatic processing and intrusion development, which can also be related to the processing elements of recent cognitive models of PTSD. Results show intrusions can be induced in the laboratory and their frequency amplified/attenuated in line with predictions. Successful manipulations include competing task type (visuospatial vs. verbal) and use of a cognitive coping strategy. Studies show that spontaneous peri-traumatic dissociation also affects intrusion frequency although attempts to manipulate dissociation have failed. It is hoped that further use of this paradigm may lead to prophylactic training for at risk groups and an improved understanding of intrusions across psychopathologies.