A prospective examination of risk factors in the development of intrusions following a trauma analog

https://doi.org/10.1016/j.brat.2017.05.001Get rights and content

Highlights

  • Data examine factors related to risk for analog intrusions and distress.

  • Peritraumatic emotion predicts intrusion frequency, intensity, and distress.

  • Physiological reactivity predicts intrusion frequency and intensity.

  • Affective priming and regulation predict intrusion frequency and distress.

Abstract

Several factors have been linked to the severity of posttraumatic distress, although retrospective designs in much of the literature limit conclusions regarding the temporal relation between risk factors and corresponding symptoms. To address these concerns, the current project employed an analog trauma paradigm to assess the impact of background characteristics, stress response, and post-stressor affect regulation on subjective distress and intrusive memories experienced during the subsequent processing of emotional stimuli. University students (N = 184; 56% female, 42% White/Non-Hispanic) were shown graphic scenes of a televised suicide. Physiological activation was recorded during exposure with emotion ratings collected following the film. Participants then viewed a sadness- or humor-eliciting prime under instructions to inhibit or naturally express emotion. Intrusions experienced during the priming film and residual distress at study's conclusion were rated prior to debriefing. Hierarchical regression identified reductions in emotional valence as a robust predictor of intrusions and distress. Sympathetic activation and exposure to the sadness prime were associated with intrusion frequency, whereas attenuated parasympathetic response predicted intrusion intensity. Expressive inhibition demonstrated a unique association with residual distress. Results suggest peritraumatic processes and post-exposure factors may hold more prominent relations with immediate trauma-related distress as compared to pre-existing survivor characteristics.

Introduction

Research over the past three decades has identified a number of factors demonstrating reliable associations with posttraumatic distress: background characteristics such as gender, trauma history, and pre-existing depression; peritraumatic responses involving emotional and physiological reactions during the event; and post-exposure factors including cued emotion and affect regulation (Cisler et al., 2010, Litz et al., 2000, Ozer et al., 2003). Despite progress in isolating correlates of posttraumatic stress, retrospective designs in much of this literature limit conclusions regarding the temporal relation between risk factors and corresponding symptoms. Analog trauma studies - protocols in which intrusive memories are elicited temporarily in non-clinical participants - have emerged as a flexible method for assessing prospective relations between risk factors and trauma-relevant outcomes (James et al., 2016). The goal of the current project was to examine the unique influence of background characteristics, stress response, and post-stressor affect manipulation on the development of intrusive memories and distress in participants exposed to an analog trauma.

Epidemiological research indicates that trauma exposure is exceedingly common, with 51–61% of the population experiencing one or more events over the course of their lifetime (Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995). Estimates of the lifetime prevalence of posttraumatic stress disorder (PTSD), by contrast, are considerably lower (4–8%; Pietrzak et al., 2011, Kessler et al., 2005), generating considerable interest in factors that may increase an individual's probability of developing disorder.

Several influential meta-analyses have examined aggregate data from the existing literature to isolate variables holding reliable associations with PTSD (e.g., Brewin et al., 2000, Ozer et al., 2003). While meta-analytic procedures enhance precision in the estimation of relations between risk factors and symptoms, inferences drawn from these data remain limited. First, the majority of studies aggregated for analysis are cross-sectional, limiting strong conclusions regarding the temporal relation between risk factors and corresponding symptoms. Second, the emphasis on general associations with total symptom severity may obscure processes by which variables confer specific risk. For example, cross-sectional analyses have identified female gender as a consistent correlate of PTSD, but it remains unclear whether women are at greater risk for uniform symptom development, whether risk is limited to specific symptom domains, or whether increased vulnerability is attributable to post-exposure factors (e.g., lack of support, social blaming) unfolding in the weeks and months following the event.

Analog trauma studies are one approach used to address the limitations of cross-sectional designs. Analog paradigms involve presenting non-clinical participants with aversive film and/or photographic stimuli to elicit intrusive thoughts and images over a discrete period (e.g., Holmes and Bourne, 2008, James et al., 2016). Intrusive memories are believed to be a hallmark symptom of PTSD, with multiple theoretical models identifying intrusions as a specific mechanism in the development of disorder (e.g., Brewin, 2001, Ehlers and Clark, 2000, Foa et al., 1989). Within the analog trauma paradigm, intrusive memories and corresponding distress are assessed in the laboratory shortly after exposure (e.g., Bomyea & Amir, 2012) and/or in the days following participation (e.g., Nixon, Cain, Nehmy, & Seymour, 2009). Predictors of subsequent intrusions vary by study but typically include background characteristics, affective response to the analog trauma, and/or experimental manipulations targeting post-exposure processing (James et al., 2016).

Background characteristics including gender, prior trauma exposure, and depression are routinely identified as general risk factors of posttraumatic stress (e.g., Brewin et al., 2000, Ozer et al., 2003) although evidence of specific links to intrusive memories remains mixed. In a recent meta-analysis of 16 analog studies, both trauma history and participant gender failed to predict intrusive images occurring in the week following exposure (Clark, Mackay, & Holmes, 2015). Selected studies outside this review have observed more frequent intrusions and higher intrusion-related distress in women relative to men (Kamboj et al., 2014, Wessel et al., 2008); however, strong evidence for trauma history and biological sex as specific risk factors for traumatic intrusions remains limited.

Pre-existing depression, by contrast, has been identified as a predictor of intrusive memories in several analog studies. Meta-analyses by Clark et al. (2015) found that lower depression scores were associated with a reduction in the odds of intrusions assessed at 1-week post-exposure. Laposa and Alden (2006) also noted prospective relations between depression and the frequency of subsequent film-related intrusions. Existing research suggests that rumination and associated cognitive biases may predispose individuals with active depression to develop more negative appraisals of the traumatic event, increasing the likelihood of unwanted memories (Angelakis and Nixon, 2015, Spinhoven et al., 2015). Mental imagery has also been proposed as a common etiological factor for both depression and traumatic intrusions (Holmes, Blackwell, Heyes, Renner, & Raes, 2016). Within this framework, mental imagery is believed to serve as an “emotional amplifier” of negative autobiographical memory including reactions to potentially traumatic events (Holmes & Mathews, 2010).

Subjective response to analog trauma stimuli has been shown to be a robust predictor of intrusive memories (Clark et al., 2015, James et al., 2016). Physiological monitoring in these designs also enables a direct assessment of the extent to which biological processes relate to subsequent intrusions. For example, Bryant, McGrath, and Felmingham (2013) identified small effects of sympathetic change on intrusive memories in women presented with aversive images (β = 0.15). Chou, La Marca, Steptoe, and Brewin (2014) observed a similar relation between post-film sympathetic activation and the frequency of intrusions in a mixed-gender sample (β = 0.17). It is important to note that specific effects in these studies failed to reach formal criteria for statistical significance although the samples available for both analyses were limited (N ≤ 45). Results are notable, however, given the paucity of research in this area and the concordance of effects with models positing a functional relation between increased arousal and the consolidation of traumatic memory (Brewin et al., 2010, Ehlers and Clark, 2000).

Parasympathetic activation during exposure may also influence the development of psychopathology, but specific relations remain largely unexplored. Consistent with models identifying parasympathetic activation as a general resilience factor (Friedman, 2007), clinical studies have found PTSD symptom severity to be associated with lower resting parasympathetic activity as well as decreased response to experimental stressors (Agorastos et al., 2013, Norte et al., 2013). Analog studies have yet to test the degree to which parasympathetic reactivity may predict aspects of intrusive memories and corresponding distress.

A final set of factors involves the manipulation of emotional and regulatory processes following analog exposure. One area gaining recent attention involves the incorporation of positive mental imagery in the treatment of mood- and anxiety-related difficulties (Holmes et al., 2016, Tsai et al., 2015, Zbozinek et al., 2015). Modifications to the analog trauma paradigm in which aversive stimuli are replaced with positively valenced films suggests the presence of common mechanisms in the generation of involuntary positive and negative memory (Clark et al., 2013, Davies et al., 2012). Research exploring the effects of mood-congruent recall suggests that positive mood induction may enhance the accessibility of positive autobiographical memory in select individuals (e.g., Holmes et al., 2016; Joormann & Siemer, 2004). From this perspective, the deliberate activation of positive affect may serve to suppress or compete with the generation of negative mental imagery associated with PTSD and co-occurring disorders.

Strategies used to manage affective responding post-exposure may further influence the development of symptoms. Expressive suppression is a volitional regulatory strategy intended to inhibit the outward display of emotion (Gross, 1998). While trait-level suppression demonstrates robust associations with elevated depression, reduced emotional well-being, negative social relations, and greater posttrauma symptom severity (Gross and John, 2003, Moore et al., 2008), few studies have explored specific links to traumatic intrusions. Existing research suggests the intentional down-regulation of expressive emotion may be associated with increased rumination, producing greater risk for the development of intrusive memories (Gross and John, 2003, Moore et al., 2008). Expressive suppression may also facilitate the development of intrusions by disrupting verbal processing systems necessary for adaptive encoding of distressing events (Brewin, 2001). Richards and Gross (2000) note that the active monitoring and online correction of expressive behavior during episodes of suppression is cognitively taxing, producing specific deficits in verbal processing and memory. Existing research linking disruptions in verbal processing to an increase in the frequency of analog intrusions (Holmes, Brewin, & Hennessy, 2004) suggests that expressive suppression following the presentation of aversive film stimuli may enhance the development of intrusive imagery.

Despite increased interest in analog trauma research, several factors relating to risk and resiliency remain unexplored. It is also relevant to note that existing studies typically target a single or small subset of factors, limiting knowledge of the interrelations between variables and their relative contribution to subsequent intrusions. Aims of the current project were to examine the unique influence of background characteristics, analog trauma response, and post-exposure affect regulation on both (a) intrusive memories experienced during the processing of subsequent emotional stimuli and (b) residual distress assessed at the study's conclusion. Data were collected as a part of a larger study targeting emotional regulation in response to an experimental stressor (Clapp, Patton, & Beck, 2015). Participants completed background measures prior to viewing a series of three films: a neutral stimulus, an analog stressor, and a final affective prime (humorous or sad). Sympathetic and parasympathetic response was collected during each film, with ratings of subjective emotion completed after each viewing period. Before presentation of the final affective prime, participants were instructed to either suppress all expressive behavior or to watch the film clip naturally. Participants then rated the frequency and intensity of intrusive memories experienced during the priming video. Ongoing distress in response to the analog trauma film was assessed at debriefing. The evaluation of intrusions experienced during a concurrent processing task is consistent with procedures used in previous research (e.g., Takarangi, Strange, & Lindsay, 2014) and was intended to examine unique influences on intrusive memories occurring in the course of valenced life events.

Based on existing research, female gender, prior Criterion-A trauma exposure, and greater severity of pre-existing depression were expected to demonstrate positive relations with all outcomes. Increased emotional and physiological reactivity during the analog trauma were also expected to predict elevations in intrusions and distress. Finally, participants viewing the positive prime and those permitted to naturally express emotion were expected to experience fewer analog symptom relative to those in the negative prime and suppression conditions.

Section snippets

Participants

Participants included 257 undergraduates enrolled in introductory psychology courses at a large southern university. Students were contacted by email and invited to participate in a study exploring “how individuals respond to viewing unpleasant stimuli.” Invitees were informed participation would involve viewing at least one graphic film depicting an actual suicide. Given the nature of the film, students receiving mental health services (i.e., counseling, medication), those reporting acute

Efficacy of the analog trauma procedure

Data supporting the efficacy of the analog trauma procedure is provided in Table 3. Participants evidenced substantial reductions in subjective valence, with the lower-limit of the 95% CI for d exceeding a 1 SD reduction in pleasantness (p < 0.001). The interval estimate for change in subjective arousal indicated a small to medium increase in emotional activation across films (p < 0.001). Point estimates of effect and corresponding intervals for change in SCL were generally consistent with

Discussion

The aim of the current study was to evaluate unique predictors of intrusive memories and subjective distress following exposure to an analog trauma. Prospective relations of background characteristics, affective response to the analog trauma film, and post-exposure manipulation of emotion and expression were examined. For these data, the combined effect of participant sex, prior trauma, and concurrent depression failed to account for statistically significant variability in the frequency or

Funding

This work was supported by grants from the National Institute of Mental Health (F31 MH083385), the National Institute of General Medical Sciences (P20GM103432), and funds provided through the University of Memphis Lillian and Morrie Moss Chair of Excellence, held by Dr. Beck.

Acknowledgments

The authors would like to acknowledge Megan L. Avery for her assistance with the coding of Criterion A trauma for this project.

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