How Expectations Shape the Formation of Intrusive Memories: An Experimental Study Using the Trauma Film Paradigm

Exploration of stress reactivity and fear conditioning on intrusive memory frequency in a conditioned-intrusion paradigm

BACKGROUND AND OBJECTIVES

The conditioned-intrusion paradigm was designed to provide insight into the relationship between fear conditioning and intrusive memory formation, which is relevant to understanding posttraumatic stress disorder symptoms and treatment. However, boundary conditions of this new paradigm have not been explored and it is currently not known whether findings from this work are valid in a clinical context.

METHODS

In the current study, we explored the relationship between stress reactivity to trauma film clips, usual exposure to violent media, renewal of fear conditioning using skin conductance as well as subjective ratings, and the effect of shock versus film clip during conditioning on the frequency of intrusive memories. An adapted fear conditioning paradigm using trauma clips as unconditional stimuli was used, and participants subsequently reported intrusive memories of the trauma clips.

RESULTS

Skin conductance responses to conditioned stimuli paired with shocks and film clips were significantly higher than conditioned stimuli paired with film clips alone. Subjective stress reactivity, previous exposure to violent media, and film valence rating were associated with the frequency of intrusive memories. No aspects of fear conditioning were associated with intrusive memories, and factor analysis suggested the fear conditioning and stress related to film clip viewing were mostly separate constructs. Similarly, content and triggers of intrusive memories were usually film-clip related rather than conditional stimulus related.

LIMITATIONS

We did not observe strong conditioning effects of the unconditional stimuli to conditional stimuli, which were shapes rather than high frequency stimuli such as faces.

CONCLUSIONS

These findings provide potential boundary conditions for this paradigm and suggest multiple ways in which the validity of the paradigm can be tested in the future.

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.

Adapting Minds: Exploring Cognition to Threatened Stimuli in the Post-COVID-19 Landscape Comparing Old and New Concerns about Pandemic

The global population has been significantly affected by the pandemic in terms of physical and mental health. According to transactional theory, individuals have undergone an adaptation process influenced by cognitive control abilities. Emotional responses to COVID-19-related stimuli may interfere with top-down attentional processes, thereby hindering adaptation. This study aimed to investigate the impact of COVID-19-related stimuli on attentional processing and to determine whether psychological factors could modulate these effects. A sample of 96 healthy undergraduate students participated in an emotional Stroop task in which they were presented with a series of stimuli, including both neutral and negative COVID-19-related as well as non-COVID-19 stimuli. COVID-19-related PTSD, as an index of distress (PTSS), and trait anxiety were evaluated. Results showed that participants were more accurate in identifying COVID-19-related stimuli compared to non-COVID-19 stimuli. Being female and having higher retrospective PTSS scores related to COVID-19 were predictive of faster reaction times for both neutral and negative COVID-19-related stimuli. This heightened attentional bias toward COVID-19-related stimuli suggests that individuals may be more sensitive to stimuli associated with the pandemic. The results suggest that the association between COVID-19 stimuli and attentional biases extends beyond emotional valence, being retrospectively influenced by mental health, suggesting potential pathways to future mental health challenges.

Trauma film viewing and intrusive memories: Relationship between salivary alpha amylase, endocannabinoids, and cortisol

The endogenous cannabinoid (ECB) system is a small molecule lipid signalling system that is involved in stress response activation and is associated with PTSD, but it is unclear whether salivary ECBs are part of the sympathetic nervous system response to stress. We conducted an adapted trauma film paradigm, where participants completed a cold pressor test (or control) while watching a 10-minute trauma film. We also collected saliva and hair samples and tested them for ECBs, cortisol, and salivary alpha amylase (sAA). As hypothesised, there were significant positive correlations between sAA activity and salivary ECB levels, particularly 2-arachidonoyl glycerol (2-AG), though ECBs were not correlated with sAA stress reactivity. Participants who had a significant cortisol response to the trauma film/stressor reported less intrusive memories, which were also less distressing and less vivid. This effect was moderated by arachidonoyl ethanolamide (AEA), where decreases in AEA post-stress were associated with more intrusive memories in cortisol non-responders only. This study provides new evidence for the role of ECBs in the sympathetic nervous system.

The relationship between multiple traumatic events and the severity of posttraumatic stress disorder symptoms – evidence for a cognitive link

Background: Previous research has shown that multiple traumatic experiences cumulatively increase the risk for the development of severe symptoms of posttraumatic stress disorder (PTSD). Yet, little is known about the specific psychological mechanism through which this increased risk comes about.Objective: In the present study, we examined a possible cognitive link between multiple traumatic events and PTSD symptom severity through dysfunctional cognitions and expectations.Methods: A sample of patients with a diagnosed PTSD (N = 70; M_Age= 42.06; 82% female) and high symptom burden (IES-R M = 79.24) was examined. On average, patients had experienced 5.31 different traumatic events. In a structural equation model, we tested the hypothesis that the relationship between multiple traumatic experiences and PTSD symptom severity is mediated through dysfunctional general cognitions and dysfunctional situation-specific expectations. General trauma-related cognitions were assessed with the Posttraumatic Cognition Inventory (PTCI) and trauma-related situational expectations were assessed with the Posttraumatic Expectations Scale (PTES).Results: The direct effect of the number of traumatic events on PTSD symptom severity was non-significant. Instead, as hypothesised, there was evidence for a significant indirect effect via dysfunctional general cognitions and situation-specific expectations.Conclusions: The current results further specify the cognitive model of PTSD by indicating that the relationship between the number of traumatic events and PTSD symptom severity is mediated through dysfunctional cognitions and expectations. These findings emphasise the importance of focused cognitive treatment approaches that seek to modify dysfunctional cognitions and expectations in people with multiple traumatic experiences.

Assessing Dysfunctional Expectations in Posttraumatic Stress Disorder: Development and Validation of the Posttraumatic Expectations Scale (PTES)

Dysfunctional expectations are a particularly important subset of cognitions that influence the development and maintenance of various mental disorders. This study aimed to develop and validate a scale to assess dysfunctional expectations in posttraumatic stress disorder (PTSD), the "Posttraumatic Expectations Scale" (PTES). In a cross-sectional study, 70 PTSD patients completed the PTES, the Posttraumatic Cognitions Inventory (PTCI), as well as measures of the severity of symptoms of PTSD and depression. The results show that the PTES has excellent internal consistency and correlates significantly with the PTCI and PTSD symptom severity. A regression analysis revealed that the PTES explained variance of PTSD symptom severity above the PTCI, supporting the incremental validity of the PTES. While the original version of the PTES comprises 81 items, short scales were constructed using the BISCUIT (best items scales that are cross-validated, unit-weighted, informative and transparent) method. The current findings provide preliminary psychometric evidence suggesting that the PTES is an internally consistent and valid novel self-report measure in patients with PTSD. However, conclusions about the psychometric properties of the PTES are limited because of the absence of criterion-related validity, factor structure evidence, variability over time/response to intervention, and test-retest reliability. Future research should use the PTES in large-scale longitudinal studies to address these aspects to further validate the scale.

Negative expectations regarding interpersonal interactions in daily life are associated with subclinical depressive symptoms in a student sample: A prospective experience sampling study

Dysfunctional expectations and interpersonal problems are associated with depression, so we measured expected emotions towards interaction partners and compared them with actual emotions. We hypothesized that, between persons, individuals with higher subclinical depression would display stronger, more stable, and less accurate negative expectations. Within persons, we hypothesized that momentary negative expectations would predict subsequent negative affect. Fifty-three students completed 6 days of Experience Sampling, consisting of one morning expectation-assessment (9 am), three assessments on actual interpersonal emotions (1 pm, 5 pm, 9 pm), and six random affect-assessments. We regressed expected emotions, experienced emotions, expectation fluctuations, and expectation violations on subclinical depression. Using mixed model analyses, we further examined whether negative expectations preceded negative affect, and whether expectation violations preceded adjustments of expectations. Higher subclinical depression predicted more negative expectations. Within persons, worse-than-expected interpersonal interactions preceded negative affect whereas better-than-expected interactions preceded reductions of negative expectations. Despite problems with skewed data, our approach appears well-suited to examine interpersonal expectations in vivo.

Can placebos reduce intrusive memories?

After traumatic experiences, intrusive memories can flash back and evoke significant distress. Here, we investigated whether the frequency and severity of intrusions can be reduced by the provision of placebo. After the (online) exposure to the trauma-film paradigm, healthy participants (N = 112) received deceptive placebo (DP), open-label placebo (OLP), or no treatment. In the DP group, participants were led to believe to receive a dopamine-modulating drug, which was supposed to disrupt the consolidation of traumatic memories, although they in fact received the same placebo tablets as the OLP group for one week. The results show that the groups did not differ in the frequency of intrusive memories after one week. However, participants receiving OLP reported a significantly reduced intensity of intrusions as compared to DP. Across groups, negative expectations about the intensity and controllability of intrusions were associated with a higher frequency of intrusions, higher distress, higher burden, and more negative appraisal. The results suggest that expectations play an important role in the emergence of intrusive memories and that some of the disabling aspects of intrusive memories can be reduced by placebo. This may carry clinical potential because placebos are an accessible, cost-effective intervention to reduce the risk of intrusive memories.