Fewer intrusions after an attentional bias modification training for perceptual reminders of analogue trauma

A systematic review and meta-analysis of experimental methods for modulating intrusive memories following lab-analogue trauma exposure in non-clinical populations

Experiencing trauma leads to intrusive memories (IMs), a hallmark symptom of post-traumatic stress disorder (PTSD), which also occurs transdiagnostically. Understanding why IMs increase or decrease is pivotal in developing interventions to support mental health. In this preregistered meta-analysis (PROSPERO: CRD42021224835), we included 134 articles (131 techniques, 606 effect sizes and 12,074 non-clinical participants) to investigate how experimental techniques alter IM frequency, intrusion-related distress and symptoms arising from lab-analogue trauma exposure. Eligible articles were identified by searching eight databases until 12 December 2023. To test potential publication biases, we employed methods including Egger's test and three-parameter selection models. We employed three-level multilevel modelling and meta-regressions to examine whether and how experimental techniques would modulate IM frequency and associated outcomes. Results showed that techniques (behavioural, pharmacological, neuromodulation) significantly reduced intrusion frequency (g = 0.16, 95% confidence interval [0.09, 0.23]). Notably, techniques aimed to reduce IMs also ameliorated intrusion-related distress and symptoms, while techniques that increased IMs exacerbated these related outcomes, thus highlighting IM's centrality in PTSD-like symptoms. Techniques tapping into mental imagery processing (for example, trauma reminder followed by playing Tetris) reduced intrusions when administered immediately after, or at a delayed time after trauma. Although our meta-analysis is limited to symptoms induced by lab-analogue trauma exposure, some lab-based results have now generalized to real-world trauma and IMs, highlighting the promising utility of lab-analogue trauma paradigms for intervention development.

Examining the role of trait anxiety and attentional bias to negative information in intrusion vulnerability following an emotionally negative event

BACKGROUND AND OBJECTIVES

Research shows that individuals with heightened trait anxiety are more likely to experience intrusions; however, the mechanism that accounts for this relationship is unclear. Two alternative hypotheses were tested to determine the nature of the associations between trait anxiety, attentional bias to negative information, and intrusion vulnerability.

METHODS

Intrusions were elicited using the trauma film paradigm, and post-event attentional bias to negative information was assessed using the dot-probe task. Participants then completed a week-long intrusions diary.

RESULTS

Results showed that attentional bias to negative information mediated the effect of heightened trait anxiety on elevated intrusion frequency. It was also revealed that heightened trait anxiety was associated with elevated intrusion-related distress, though attentional bias to negative information did not mediate this relationship.

LIMITATIONS

Our sample was comprised of undergraduate students who were not selected based on a previous pathology. Replication in clinical samples is warranted.

CONCLUSIONS

These findings provide new insight regarding individual differences in the experience of intrusions and suggest that both the frequency and distress associated with intrusions could represent clinical targets.

A systematic review and meta-analysis of the effect of cognitive interventions to prevent intrusive memories using the trauma film paradigm

There is an unmet need for effective early interventions that can relieve initial trauma symptoms and reduce symptoms of posttraumatic stress disorder (PTSD). We evaluated the efficacy of cognitive interventions compared to control in reducing intrusion frequency and PTSD symptoms in healthy individuals using the trauma film paradigm, in which participants view a film with aversive content as an experimental analogue of trauma exposure. A systematic literature search identified 41 experiments of different cognitive interventions targeting intrusions. In the meta-analysis, the pooled effect size of 52 comparisons comparing cognitive interventions to no-intervention controls on intrusions was moderate (g = -0.46, 95% CI [-0.61 to -0.32], p < .001). The pooled effect size of 16 comparisons on PTSD symptoms was also moderate (g = -0.31, 95% CI [-0.46 to -0.17], p < .001). Both visuospatial interference and imagery rescripting tasks were associated with significantly fewer intrusions than controls, whereas verbal interference and meta-cognitive processing tasks showed nonsignificant effect sizes. Interventions administered after viewing the trauma film showed significantly fewer intrusions than controls, whereas interventions administered during film viewing did not. No experiments had low risk of bias (ROB), 37 experiments had some concerns of ROB, while the remaining four experiments had high ROB. To the best of our knowledge, this is the first meta-analysis investigating the efficacy of cognitive interventions targeting intrusions in non-clinical samples. Results seem to be in favour of visuospatial interference tasks rather than verbal tasks. More research is needed to develop an evidence base on the efficacy of various cognitive interventions and test their clinical translation to reduce intrusive memories of real trauma.

Cognitive Bias Modification bei Symptomen der Posttraumatischen Belastungsstörung

Kognitive Modelle der Posttraumatischen Belastungsstörung (PTBS) gehen davon aus, dass eine dysfunktionale Informationsverarbeitung in den Bereichen Aufmerksamkeit, Interpretation, Bewertung und Gedächtnis einen wichtigen Faktor für das Auftreten und die Aufrechterhaltung der PTBS darstellt. Parallel zeigen verschiedenste Entwicklungen in der klinisch-experimentellen Forschung, dass es möglich sein könnte, solche kognitiven Verzerrungen mithilfe von Cognitive Bias Modification (CBM)-Trainings zu modifizieren. In diesem Beitrag geben wir einen narrativen Überblick über die CBM-Forschung im Kontext von Trauma und PTBS, im experimentellen sowie klinisch-angewandten Bereich. Zudem werden Herausforderungen und neue Forschungslinien für die CBM-Forschung im Kontext der PTBS vorgestellt und diskutiert.

The independent roles of attentional engagement with, and disengagement from, negative information in intrusive re-experiencing of negative events

BACKGROUND AND OBJECTIVES

Intrusive re-experiencing of negative events represents a key vulnerability factor for Post-Traumatic Stress Disorder. Thus, delineating attentional mechanisms that might contribute to key facets of intrusive re-experiencing would be highly advantageous. The present study sought to evaluate the novel hypothesis that biased attentional engagement and disengagement differentially contribute to two central facets of intrusive re-experiencing, frequency and controllability, respectively.

METHODS

One hundred undergraduates were exposed to an acutely negative event, followed by completion of an attentional task that permitted the discrete assessment of biased attentional engagement with, and biased attentional disengagement from, negative vs. non-negative information. Intrusions concerning this negative event were assessed daily, for the subsequent seven days, by means of an electronic diary.

RESULTS

Results revealed that enhanced attentional engagement with negative vs. non-negative information predicted unique variance in intrusion frequency, whereas impaired attentional disengagement from negative vs. non-negative information predicted unique variance in intrusion controllability. These intrusion-linked patterns of attentional selectivity were evident at shorter (500 ms) stimulus exposure durations only, and not at longer (1000 ms) stimulus exposure durations.

LIMITATIONS

The current study did not assess attentional selectivity prior to the negative event. Additionally, a time-based approach, rather than an event-based approach, was employed in the assessment of intrusions.

CONCLUSIONS

The current findings suggest that engagement bias and disengagement bias may underpin differing facets of intrusive re-experiencing, raising the possibility that therapeutically targeting each type of attentional bias may attenuate a distinctive aspect of intrusive re-experiencing.

Attentional processes and contamination-related intrusion distress

Whilst people with high contamination fear may not experience a greater number of contamination-related intrusions than people with low contamination fear, they tend to experience heightened distress in response to such intrusions. The aim of the present study was to test the hypothesis that attentional bias to contamination-relevant information, and the variability of this attentional bias, moderates the degree to which high contamination fearful but not low contamination fearful individuals experience distress in response to contamination-related intrusions. Individuals with high (n = 31) or low (n = 44) contamination fear completed a lab-based session including questionnaires, a dot-probe measure of contamination-related attentional bias and attentional bias variability, and a contamination stressor video. Participants then completed a week-long contamination intrusions diary. There were significant differences in intrusion distress between those with low and high contamination fear in the anticipated direction, and attentional bias significantly moderated this relationship. Regardless of contamination fear level, greater attentional bias variability was associated with greater intrusion distress. These findings suggest that reducing attentional bias variability could potentially help to reduce distress elicited by contamination-related intrusions, while also highlighting the fact that attentional bias towards threat may protect against such distress in low contamination fearful individuals.

Intrusive memories and voluntary memory of a trauma film: Differential effects of a cognitive interference task after encoding

Methods to reduce intrusive memories (e.g., of traumatic events) should ideally spare voluntary memory for the same event (e.g., to report on the event in court). Single-trace memory accounts assume that interfering with a trace should impact both its involuntary and voluntary expressions, whereas separate-trace accounts assume these two can dissociate, allowing for selective interference. This possibility was investigated in 3 experiments. Nonclinical participants viewed a trauma film followed by an interference task (Tetris game-play after reminder cues). Next, memory for the film was assessed with various measures. The interference task reduced the number of intrusive memories (diary-based, Experiments 1 and 2), but spared performance on well-matched measures of voluntary retrieval-free recall (Experiment 1) and recognition (Experiments 1 and 2)-challenging single-trace accounts. The interference task did not affect other measures of involuntary retrieval-perceptual priming (Experiment 1) or attentional bias (Experiment 2). However, the interference task did reduce the number of intrusive memories in a laboratory-based vigilance-intrusion task (Experiments 2 and 3), irrespective of concurrent working memory load during intrusion retrieval (Experiment 3). Collectively, results reveal a robust dissociation between intrusive and voluntary memories, having ruled out key methodological differences between how these two memory expressions are assessed, namely cue overlap (Experiment 1), attentional capture (Experiment 2), and retrieval load (Experiment 3). We argue that the inability of these retrieval factors to explain the selective interference is more compatible with separate-trace than single-trace accounts. Further theoretical developments are needed to account for this clinically important distinction between intrusive memories and their voluntary counterpart. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Spatio-temporal associations with memory cues are linked to analogue traumatic intrusions

Trauma survivors with post-traumatic stress disorder (PTSD) frequently experience intrusive trauma memories associated with a feeling of "nowness". Information-processing models of PTSD ascribe these symptoms to an insufficient integration of memories with their spatio-temporal context in the past, turning them into powerful stressors. Here, we tested the idea that automatic associations of trauma reminders with the present or the past predict intrusive memories. We instructed 96 healthy participants to view two different traumatic films. Participants then underwent a computerized training that established implicit contingencies between film reminder pictures with the verbal responses "now" or "past" to increase and reduce intrusions, respectively. The training successfully altered implicit spatio-temporal associations for film reminder stimuli on a subsequent Implicit Association Test (IAT). There were no additional transfer effects for tense usage during a free recall task after one week and for the development of intrusion symptoms (one-week diary, retrospective questionnaire). However, participants who associated one film more strongly with the present and the other with the past consistently reported relatively more intrusive memories related to the former film. Thus, our results lend support to information processing models of PTSD and warrant further investigation of the causal role of implicit associations with spatio-temporal information.

Intrusive memories of trauma: A target for research bridging cognitive science and its clinical application

Intrusive memories of a traumatic event can be distressing and disruptive, and comprise a core clinical feature of post-traumatic stress disorder (PTSD). Intrusive memories involve mental imagery-based impressions that intrude into mind involuntarily, and are emotional. Here we consider how recent advances in cognitive science have fueled our understanding of the development and possible treatment of intrusive memories of trauma. We conducted a systematic literature search in PubMed, selecting articles published from 2008 to 2018 that used the terms "trauma" AND ("intrusive memories" OR "involuntary memories") in their abstract or title. First, we discuss studies that investigated internal (neural, hormonal, psychophysiological, and cognitive) processes that contribute to intrusive memory development. Second, we discuss studies that targeted these processes using behavioural/pharmacological interventions to reduce intrusive memories. Third, we consider possible clinical implications of this work and highlight some emerging research avenues for treatment and prevention, supplemented by new data to examine some unanswered questions. In conclusion, we raise the possibility that intrusive memories comprise an alternative, possibly more focused, target in translational research endeavours, rather than only targeting overall symptoms of disorders such as PTSD. If so, relatively simple approaches could help to address the need for easy-to-deliver, widely-scalable trauma interventions.

Single-Session Attention Bias Modification Training in Victims of Work-Related Accidents

Individuals who experienced traumatic work-related accidents frequently show cognitive deficits and biased processing of trauma-relevant information, which, in turn, could increase the risk of further accidents. The attention bias modification training (ABMT) is designed to reduce hypervigilance toward and enhance attentional disengagement from threat stimuli. The aim of the present study was to assess whether it is possible to implicitly reduce the attentional bias toward trauma-related stimuli through a single session of ABMT in individuals who experienced a traumatic occupational accident. Nineteen individuals who had experienced a traumatic work-related accident and 11 workers who never experienced a work accident (control group) underwent a preliminary assessment of cognitive performance (executive functions and sustained attention) and an evaluation of the attentional bias toward accident-related pictures by means of a dot-probe task. The results showed that injured workers performed more poorly than controls in tasks of executive functions and concentration abilities. Also, injured workers showed an attentional bias toward trauma reminders (i.e., faster reaction times to probes replacing trauma-related pictures). Injured workers were then randomly allocated to a single-session of ABMT (N = 10) or to an Attention Control Condition (ACC; N = 9). After the training, the dot-probe task was administered again to assess changes in the attentional bias toward trauma-relevant pictures. Injured workers who underwent the ABMT, but not those who underwent the ACC, showed a significant reduction of the attentional bias from pre- to post-training. Overall, these results support previous findings reporting an association between traumatic occupational accidents and cognitive dysfunctions. More importantly, these preliminary findings add to a growing body of evidence suggesting the effectiveness of a short ABMT in reducing the attentional bias after a traumatic workplace accident.

Susceptibility to others' emotions moderates immediate self-reported and biological stress responses to witnessing trauma

BACKGROUND

The peri-traumatic stress response is a strong predictor of symptom development after trauma exposure. Regarding witnessing trauma, the stress response might depend on the susceptibility to others' emotions (emotional contagion, EC). This study investigated whether EC moderates the immediate stress response using a trauma film paradigm.

METHODS

Ninety-five healthy participants were randomly exposed to a trauma or a neutral film. Perceived stressfulness of the film and pre-to post-film changes in self-reported anxiety, heart rate and saliva cortisol levels were assessed. EC towards negative and positive emotions was measured using the emotional contagion scale and its emotion-specific subscales.

RESULTS

Overall, the trauma film was perceived as distressing and elicited an increase in self-reported anxiety, heart rate and saliva cortisol levels relative to the neutral film. EC towards negative emotions was positively related to the perceived stressfulness of the film, increased anxiety and increased heart rate. The association with saliva cortisol levels was also in the expected direction, but not statistically significant. These associations were not found for EC towards positive emotions.

DISCUSSION

EC towards negative emotions may be an important predictor of trauma exposure outcomes. Further research should clarify its specific contribution in witnessing and undergoing trauma.

Intrusive Memories of Trauma in the Laboratory: Methodological Developments and Future Directions

Purpose of the Review

Intrusive memories are those that spring to mind unbidden, e.g. sensory recollections of stressful/traumatic events. We review recent methods to monitor intrusions of a stressor (a trauma film) within the laboratory.

Recent Findings

Recent studies suggest three main methodologies after viewing a trauma film by which to monitor intrusions in the laboratory: during post-film rest periods, after exposure to trigger cues, and while performing an ongoing task. These approaches allow factors to be tested (e.g. psychological or pharmacological) that may influence the frequency of occurrence of intrusions.

Summary

We raise methodological considerations to guide trauma film studies using intrusion monitoring in the laboratory to complement monitoring approaches in daily life (e.g. diaries). Intrusion monitoring in the laboratory also confers greater experimental control and may open novel research avenues, to advance intervention development to mitigate problematic intrusive memory symptoms.

Modification of cognitive biases related to posttraumatic stress: A systematic review and research agenda

Cognitive models of Posttraumatic Stress Disorder (PTSD) postulate that cognitive biases in attention, interpretation, and memory represent key factors involved in the onset and maintenance of PTSD. Developments in experimental research demonstrate that it may be possible to manipulate such biases by means of Cognitive Bias Modification (CBM). In the present paper, we summarize studies assessing cognitive biases in posttraumatic stress to serve as a theoretical and methodological background. However, our main aim was to provide an overview of the scientific literature on CBM in (analogue) posttraumatic stress. Results of our systematic literature review showed that most CBM studies targeted attentional and interpretation biases (attention: five studies; interpretation: three studies), and one study modified memory biases. Overall, results showed that CBM can indeed modify cognitive biases and affect (analog) trauma symptoms in a training congruent manner. Interpretation bias procedures seemed effective in analog samples, and memory bias training proved preliminary success in a clinical PTSD sample. Studies of attention bias modification provided more mixed results. This heterogeneous picture may be explained by differences in the type of population or variations in the CBM procedure. Therefore, we sketched a detailed research agenda targeting the challenges for CBM in posttraumatic stress.

Clinical efficacy of attentional bias modification procedures: an updated meta-analysis

CONTEXT

Attentional bias modification (ABM) treatment is a promising intervention tool for a variety of clinical conditions.

OBJECTIVES

This study provides an updated review of the clinical effect of ABM by employing standard meta-analytic procedures to (a) estimate the average effect size of ABM in reducing both attention bias (AB) and symptoms, (b) estimate the average effect size for different conditions (e.g., anxiety, depression, and substance abuse), (c) test possible variables that may moderate the effect sizes, and (d) investigate the relationship between preexistent AB and the reduction in AB and symptoms.

METHOD

We included 43 controlled trials with a total of 2,268 participants providing 47 group comparisons (i.e., training vs. control condition). Inclusion criteria were as follows: AB was specifically targeted to reduce symptomatology and emotional vulnerability; participants were randomized to the experimental conditions; a control condition (defined as sham training) existed; symptoms were assessed at least postintervention; sufficient data were provided to allow effect size estimation.

RESULTS

We obtained a small overall effect size on symptoms postintervention, g = 0.160, 95% confidence interval (CI) = [0.055, 0.265], driven by anxiety studies, g = 0.260, 95% CI = [0.132, 0.388], and studies conducted in healthy participants, g = 0.211, 95% CI = [0.046, 0.375]; no significant effect sizes were found postintervention for other symptom categories.

CONCLUSION

The therapeutic benefit of ABM is rather small for anxiety, while the amount of data for other symptom categories is limited. We argue that more efficient, psychometrically sound procedures are needed for assessing and modifying AB.

Involuntary Memories and Dissociative Amnesia: Assessing Key Assumptions in PTSD Research

Autobiographical memories of trauma victims are often described as disturbed in two ways. First, the trauma is frequently re-experienced in the form of involuntary, intrusive recollections. Second, the trauma is difficult to recall voluntarily (strategically); important parts may be totally or partially inaccessible-a feature known as dissociative amnesia. These characteristics are often mentioned by PTSD researchers and are included as PTSD symptoms in the DSM-IV-TR (American Psychiatric Association, 2000). In contrast, we show that both involuntary and voluntary recall are enhanced by emotional stress during encoding. We also show that the PTSD symptom in the diagnosis addressing dissociative amnesia, trouble remembering important aspects of the trauma is less well correlated with the remaining PTSD symptoms than the conceptual reversal of having trouble forgetting important aspects of the trauma. Our findings contradict key assumptions that have shaped PTSD research over the last 40 years.

Dwelling on potential threat cues: an eye movement marker for combat-related PTSD

BACKGROUND

Although several studies have documented an attentional bias toward threat in posttraumatic stress disorder (PTSD), the nature of this bias has not been clearly delineated. The present study utilized eye tracking technology to delineate the time course and components of attentional bias for threat cues in combat-related PTSD.

METHODS

Veterans with PTSD (n = 21), combat-exposed veterans without PTSD (n = 16), and nonveteran controls (n = 21) viewed emotional expressions (fearful, disgusted, happy) paired with neutral expressions for 3 s presentations.

RESULTS

Veterans with PTSD maintained attention longer on the fearful and disgusted expressions relative to the happy expression. This negativity bias was sustained over the course of the 3 s trials, and robustly distinguished veterans with PTSD from both veterans without PTSD and nonveteran controls.

CONCLUSIONS

Dwelling on potential threat cues may reflect current PTSD symptoms, or it could reflect a cognitive vulnerability factor for PTSD.

Analogue trauma results in enhanced encoding of threat information at the expense of neutral information

This study investigated whether trauma-related stimuli are preferentially processed at the expense of ongoing processing of neutral stimuli. Participants in the experimental group viewed negative pictures (Trauma) as an analogue trauma induction. Participants in the control group viewed visually similar neutral pictures (Neutral Match). In a Rapid Serial Visual Presentation (RSVP) task participants identified two target pictures. The first target (T1) was a neutral picture, whereas the second target (T2) was a familiar negative or neutral picture or a new neutral or negative picture. In line with hypotheses, only participants in the experimental group showed preferential processing of Trauma pictures. In the experimental group, negative T2 impaired the identification of (neutral) T1 if the T2 immediately followed the T1 in the RSVP stream. The results are consistent with a processing priority of trauma-related information, apparently at the expense of the ongoing processing of neutral information.