Can placebos prevent intrusive memories?

After traumatic experiences, intrusive memories can flash back and evoke significant distress. Here, we investigated whether the occurrence of intrusions can be prevented by placebo. After the exposure to an experimental psychopathology model of psychological trauma, healthy participants (N=112) were randomised to deceptive placebo (DP), open-label placebo (OLP), or a no-treatment control group. The results show that one week later, the groups did not differ in the frequency of intrusive memories. However, participants receiving OLP reported the lowest intensity of intrusions. Participants receiving DP reported the lowest burden of intrusions. Across groups, the expectation that intrusions will be intense and hardly controllable was associated with a higher frequency of intrusions, higher distress, higher burden, and more negative appraisal. The results suggest that expectations play a crucial role in the emergence of intrusive memories and that at least some of the disabling aspects of intrusive memories can be reduced by placebo.

Intranasal oxytocin administration impacts the acquisition and consolidation of trauma-associated memories: a double-blind randomized placebo-controlled experimental study in healthy women

Intrusive memories are a hallmark symptom of post-traumatic stress disorder (PTSD) and oxytocin has been implicated in the formation of intrusive memories. This study investigates how oxytocin influences the acquisition and consolidation of trauma-associated memories and whether these effects are influenced by individual neurobiological and genetic differences. In this randomized, double-blind, placebo-controlled study, 220 healthy women received either a single dose of intranasal 24IU oxytocin or a placebo before exposure to a trauma film paradigm that solicits intrusive memories. We used a “general random forest” machine learning approach to examine whether differences in the noradrenergic and hypothalamic-pituitary-adrenal axis activity, polygenic risk for psychiatric disorders, and genetic polymorphism of the oxytocin receptor influence the effect of oxytocin on the acquisition and consolidation of intrusive memories. Oxytocin induced significantly more intrusive memories than placebo did (t(188.33) = 2.12, p = 0.035, Cohen’s d = 0.30, 95% CI 0.16–0.44). As hypothesized, we found that the effect of oxytocin on intrusive memories was influenced by biological covariates, such as salivary cortisol, heart rate variability, and PTSD polygenic risk scores. The five factors that were most relevant to the oxytocin effect on intrusive memories were included in a Poisson regression, which showed that, besides oxytocin administration, higher polygenic loadings for PTSD and major depressive disorder were directly associated with a higher number of reported intrusions after exposure to the trauma film stressor. These results suggest that intranasal oxytocin amplifies the acquisition and consolidation of intrusive memories and that this effect is modulated by neurobiological and genetic factors. Trial registration: NCT03031405.

Feasibility of an adjunctive cognitive task in the treatment of posttraumatic stress disorder

Visuospatial cognitive tasks that influence memory reconsolidation may be of benefit in reducing intrusive memories for traumatic events when used as an adjunct to trauma-focused psychotherapy. We conducted a feasibility assessment of a protocol that involved the use of a visuospatial cognitive task, the Tetris intervention, alongside routine exposure-based treatment for posttraumatic stress disorder (PTSD). Participants were inpatients attending for PTSD treatment at a psychiatric hospital. The Tetris intervention was administered on three occasions when imaginal exposure had formed part of the treatment session. Using a phone app, participants also monitored intrusive memories over a 3-week period. Feasibility outcomes were fully met for the demand, implementation, practicality and adaptability criteria. Only a single criterion was not met for each of the acceptability and implementation criteria. Limited-efficacy testing outcomes are also discussed. Overall, the findings from our feasibility study indicated viability of the protocol, which involved implementation of the Tetris intervention alongside routine exposure-based treatment for PTSD, in a clinical inpatient setting.

Cognitive Flexibility Moderates the Efficacy of a Visuospatial Intervention Following Exposure to Analog Trauma

Objective: Intrusive memories are the hallmark feature of Post-Traumatic-Stress-Disorder (PTSD). Recent studies have found that a visuospatial intervention after viewing traumatic films reduces intrusive memories in healthy individuals. However, many individuals still exhibit high levels of symptoms following such an intervention, warranting continued investigation into specific characteristics moderating intervention effect. One such candidate is cognitive flexibility, defined as the ability to update behavior in accordance with contextual demands. The present study aimed at examining the interactive effect of cognitive flexibility and a visuospatial intervention on intrusive memories, predicting that higher flexibility would be linked to stronger intervention effects. Method: Sixty participants (Mage = 29.07, SD = 4.23) completed a performance-based paradigm evaluating cognitive flexibility, watched traumatic films, and were allocated to either an intervention or control group. Intrusions were assessed by means of laboratory and ambulatory assessment, and the Impact of Events Scale – Revised (IES-R). Results: Participants in the intervention group experienced fewer laboratory intrusions than the control group. However, this effect was moderated by cognitive flexibility: Whereas individuals with below-average cognitive flexibility did not benefit from the intervention, it was significantly beneficial for individuals with average and above-average cognitive flexibility. No group differences emerged in the number of ambulatory intrusions or IES-R scores. However, cognitive flexibility was negatively correlated with IES-R scores across both groups. Conclusions: These results highlight the significant role of cognitive flexibility in intrusion development, both in general and as a moderator of a visuospatial interventions. Future studies should investigate effects’ generalizability to clinical samples.

Lonely in the dark: trauma memory and sex-specific dysregulation of amygdala reactivity to fear signals

Loneliness exacerbates psychological distress and increases the risk of psychopathology after trauma exposure. The prevalence of trauma-associated disorders varies substantially between sexes, and accumulating evidence indicates sex-specific effects of loneliness. However, it is still unclear whether a lack of social connectedness affects trauma-induced intrusions and the neural processing of fear signals. Moreover, it is uncertain, whether loneliness plays a different role in women and men. We used a prestratification strategy and recruited n=47 (n=20 women) healthy individuals with high loneliness and n=35 controls (n=18 women). Participants were exposed to an experimental trauma and evoked intrusive thoughts in daily life were monitored for three consecutive days. Functional magnetic resonance imaging was used to assess neural habituation to fearful faces and fear learning (conditioning and extinction) prior to trauma exposure. The total number of intrusions and amygdala reactivity in neural fear processing served as the primary study outcomes. Our results revealed a significant interaction between loneliness and sex such that loneliness was associated with more intrusions in men, but not in women. A similar pattern emerged at the neural level, with both reduced amygdala habituation to repeated fearful faces and amygdala hyperreactivity during the conditioning of fear signals in lonely men, but not in women. Our findings indicate that loneliness may confer vulnerability to intrusive memories after trauma exposure in healthy men and that this phenotype relates to altered limbic processing of fear signals. Collectively, interventions targeting social connectedness may mitigate the sequelae of traumatic experiences.

Correction: Reducing Intrusive Memories of Childhood Trauma Using a Visuospatial Intervention: Case Study in Iceland (Preprint)

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Reaching people soon after a traumatic event: an exploratory observational feasibility study of recruitment in the emergency department to deliver a brief behavioral intervention via smartphone to prevent intrusive memories of trauma

Background The current study explored how to recruit patients soon after a traumatic event, to deliver a novel intervention in a new emergency department in Sweden. This brief behavioral intervention aims to prevent intrusive memories and is delivered soon after trauma in the emergency department. In the UK, it has shown promising results. Traumatic events resulting in admission to the emergency department (e.g., road traffic accidents) may result in subsequent mental health problems such as post-traumatic stress disorder, where intrusive memories of the trauma constitute a core clinical feature. Early interventions that prevent intrusive memories after psychological trauma are lacking. Specific aims were to explore identification of eligible patients (aim 1), fitting in with emergency department staff routines to deliver the study protocol (aim 2), and using the patients’ own smartphones to deliver intervention/control task (aim 3). Two changes to the previous study were (i) extending the trauma types included (ii) a new control condition, also by smartphone. Methods This is an explorative observational study. Data was both analyzed descriptively and using the Framework method. Results We identified several possible ways to recruit patients, and establish a sense of embeddedness in the Swedish emergency department context and a positive appreciation from staff. The study protocol was tested with 8 participants. Tasks both in the intervention and control condition were readily delivered via patients’ own smartphones. Conclusion Recruitment of patients and smartphone delivery of the intervention indicates initial feasibility. Researcher presence and administration of study procedures was successfully fitted to emergency department routines and well received by staff. Further pilot work is warranted, underscoring the importance of our collaboration between nursing and psychology.