Contextual representations of negative images modulate intrusion frequency in an intrusion provocation paradigm

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.

The application of imagery rescripting to intrusive autobiographical memories in depression

Intrusive autobiographical memories are a prominent feature of depression implicated in the onset and course of the disorder. Current cognitive behavioural treatment of depression does not specify techniques to address intrusive memories. Imagery rescripting has been demonstrated to be effective in the treatment of trauma-related intrusive memories. This paper illustrates the application of imagery rescripting as a stand-alone treatment for two patients experiencing a current major depressive episode. The two cases are described in detail and follow-up data are reported. Both patients experienced clinically significant and reliable change in their depression scores and no longer met criteria for a current major depressive episode at post-assessment, with gains maintained at 3-month follow-up. Implications are discussed for the theoretical mechanisms of change of this intervention as well as methods to overcome common treatment obstacles that arise in depression.

Key learning aims

(1)

Right Hemisphere Memory Bias Does Not Extend to Involuntary Memories for Negative Scenes

Attention is unequally distributed across the visual field. Due to greater right than left hemisphere activation for visuospatial attention, people attend slightly more to the left than the right side. As a result, people voluntarily remember visual stimuli better when it first appears in the left than the right visual field. But does this effect-termed a right hemisphere memory bias-also enhance involuntary memory? We manipulated the presentation location of 100 highly negative images (chosen to increase the likelihood that participants would experience any involuntary memories) in three conditions: predominantly leftward (right hemisphere bias), predominantly rightward (left hemisphere bias), or equally in both visual fields (bilateral). We measured subsequent involuntary memories immediately and for 3 days after encoding. Contrary to predictions, biased hemispheric processing did not affect short- or long-term involuntary memory frequency or duration. Future research should measure hemispheric differences at retrieval, rather than just encoding.

The influence of ruminative processing mode on the trajectory of intrusive memories following a negative mood induction

BACKGROUND AND OBJECTIVES

Rumination following an event, particularly in an abstract as opposed to concrete processing mode, is associated with increased intrusive memory frequency. However, the temporal trajectory of intrusive memories following abstract and concrete rumination remains unclear. We examined the association between processing mode and the frequency of intrusive memories over a 6-h time period following a negative mood induction.

METHODS

One hundred and sixteen community participants watched a video sequence designed to induce negative mood. Participants were then randomised into condition (abstract, concrete or distraction) and completed a verbally mediated task designed to induce the respective processing mode. Participants then completed hourly ratings of rumination and intrusive memories about the video after leaving the laboratory.

RESULTS

Negative mood and intrusive memories were reliably induced. There were no differences in the frequency of intrusive memories between the abstract and concrete conditions. In contrast, participants in the distraction condition reported significantly more sensory intrusive memories than either ruminative condition. Three classes were found among participants following the video (intrusion free, rapid remitters, slow remitters). Condition was not predictive of class membership.

LIMITATIONS

It cannot be ruled out that the differences between rumination and distraction conditions were due to task differences.

CONCLUSIONS

In contrast to previous findings, our results suggest that any form of rumination about an event (whether in an abstract or concrete mode) may temporarily result in fewer intrusive memories in comparison to distraction. Processing mode does not appear to predict particular trajectories of intrusions following a mood induction.

Angiotensin involvement in trauma processing-exploring candidate neurocognitive mechanisms of preventing post-traumatic stress symptoms

The angiotensin-II antagonist losartan is a promising candidate that has enhanced extinction in a post-traumatic stress disorder (PTSD) animal model and was related to reducing PTSD symptom development in humans. Here, we investigate the neurocognitive mechanisms underlying these results, testing the effect of losartan on data-driven and contextual processing of traumatic material, mechanisms proposed to be relevant for PTSD development. In a double-blind between-subject design, 40 healthy participants were randomised to a single oral dose of losartan (50 mg) or placebo, 1 h before being exposed to distressing films as a trauma analogue while heart rate (HR) was measured. Peritraumatic processing was investigated using blurry picture stimuli from the films, which transformed into clear images. Data-driven processing was measured by the level of blurriness at which contents were recognised. Contextual processing was measured as the amount of context information retrieved when describing the pictures' contents. Negative-matched control images were used to test perceptual processing of peripheral trauma-cues. Post-traumatic stress symptoms were assessed via self-report questionnaires after analogue trauma and an intrusion diary completed over 4 days following the experiment. Compared to placebo, losartan facilitated contextual processing and enhanced detail perception in the negative-match pictures. During the films, the losartan group recorded lower HR and higher HR variability, reflecting lower autonomic stress responses. We discuss potential mechanisms of losartan in preventing PTSD symptomatology, including the role of reduced arousal and increased contextual processing during trauma exposure, as well as increased threat-safety differentiation when encountering peripheral trauma-cues in the aftermaths of traumatic events.

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.

Imagining trauma: Memory amplification and the role of elaborative cognitions

BACKGROUND AND OBJECTIVES

Trauma victims, such as war veterans, often remember additional traumatic events over time: the "memory amplification effect". This effect is associated with the re-experiencing symptoms of post-traumatic stress disorder (PTSD), including frequent and intrusive images of the trauma. One explanation for memory amplification is that people gradually incorporate new, imagined information about the trauma with what they actually experienced, leading to an amplified memory for what actually happened. We investigated this proposal here.

METHODS

Participants viewed highly negative and graphic photographs and recorded their intrusions. Critically, we instructed some participants to elaborate on their intrusions-that is, we asked them to imagine details about the trauma beyond what they actually witnessed. We assessed memory for the traumatic photos twice, 24-h apart.

RESULTS

The elaboration condition experienced fewer intrusions about the photos compared to the control condition. Furthermore, the elaboration condition were less susceptible to memory amplification compared to controls.

LIMITATIONS

The use of negative photos allowed experimental control, however does not permit generalization of our findings to real-world traumatic experiences.

CONCLUSIONS

Our findings suggest that effortful imagination of new trauma-related details leads to a reduction in intrusions and an increased tendency to not endorse trauma exposure over time. One explanation for this finding is that elaboration enhanced conceptual processing of the trauma analogue, therefore reducing intrusions. Critically, this reduction in intrusions affected participants' tendency to endorse trauma exposure, which is consistent with the reality-monitoring explanation for memory amplification.

Can't get it out of my mind: A systematic review of predictors of intrusive memories of distressing events

Intrusive memories, when persistent and distressing, are theorized to underlie a range of transdiagnostic psychological symptoms and associated impairment. However, little is known about factors predicting the development and persistence of intrusive memories. The aim of this systematic review is to evaluate the literature on pre-event, event-based, and post-event predictors of intrusive memories. A systematic review was conducted, searching for studies that examined intrusive, event-based memories. One hundred and six articles were identified from PsycInfo, PubMed, and Medline databases. Experimental and prospective studies with clinical (N = 14) and nonclinical (N = 92) samples were critically reviewed, provided the inclusion of an analogue stressor with nonclinical samples, and that intrusive memories frequency and/or distress were assessed as primary dependent variables. Pre-existing psychopathology and pre-event appraisal style appear to predict intrusive memories (small to medium effects), whereas trait dissociation did not predict intrusive memories. Of studies examining event-based predictors, higher data-driven processing appears to predict intrusive memories with generally large effects. Post-event negative appraisals consistently predicted intrusive memories (medium to large effects), and preliminary evidence suggests higher post-event conceptual processing predicting fewer intrusive memories. This review synthesizes findings regarding a broad range of pre-event, event-based, and post-event factors that may influence the development of intrusive memories. Methodological issues of current paradigms and the lack of emphasis on memory retrieval processes limit our understanding of what predicts intrusive memory persistence. These limitations are particularly important given that individuals typically seek treatment for distressing intrusive memories once a memory has been fully consolidated, where retrieval processes are of utmost importance. (PsycINFO Database Record

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.