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. Author manuscript; available in PMC: 2013 Jun 1.
Published in final edited form as: J Behav Ther Exp Psychiatry. 2011 Dec 13;43(2):844–848. doi: 10.1016/j.jbtep.2011.12.001

The relationship between cognitive control and posttraumatic stress symptoms

Jessica Bomyea 1, Nader Amir 1, Ariel J Lang 2,3,*
PMCID: PMC3262901  NIHMSID: NIHMS346466  PMID: 22200545

Abstract

Background and Objectives

Recently researchers have theorized that individual differences in cognitive control (i.e., the ability to complete goal-directed behavior by actively maintaining information while inhibiting irrelevant information) may elucidate processes involved in disorders characterized by intrusive thoughts and memories. By this account, the relationship between cognitive control and emotional disorders would be specific to symptoms associated with intrusive cognitions, such as re-experiencing symptoms of posttraumatic stress disorder (PTSD).

Methods

In the present study, 77 undergraduate participants with a self-reported history of trauma exposure were administered assessments of cognitive control (working memory capacity; WMC), PTSD symptoms, trait anxiety, and depression. PTSD symptoms from each of the three symptom clusters (re-experiencing, avoidance, and hyperarousal) were predicted from trait anxiety, depression, and WMC performance scores using separate regression models.

Results

After controlling for trait anxiety and depression, there was a negative, statistically significant relationship between cognitive control and re-experiencing symptoms but not avoidance or hyperarousal symptoms.

Limitations

The study was completed cross-sectionally and did not include a diagnostic assessment of PTSD.

Conclusions

Findings add to extant literature suggesting a relationship between cognitive control and intrusive cognitions. Moreover, the present study expands the current literature by demonstrating the specificity of this relationship within individuals with varying degrees of PTSD symptom severity.

1. Introduction

A significant minority of individuals develop posttraumatic stress disorder (PTSD), which is characterized by chronic and debilitating re-experiencing, avoidance, and hyperarousal symptoms, after experiencing a traumatic or life threatening event (American Psychiatric Association, 2000; Kessler, Chiu, Demler, & Walters, 1995; McNally, Bryant, & Ehlers, 2003). Individual difference variables present before, during, or after trauma may elucidate processes by which individuals naturally recover or develop pathology. Recently, researchers have posited that deficits in cognitive control may be implicated in the etiology and maintenance of PTSD (e.g., Anderson & Levy, 2009; Joormann, Yoon, & Siemer, 2010; Verwoerd, de Jong, & Wessel, 2008). Cognitive control (also referred to as attention control, executive attention, or executive functioning; see Wessel, Overwijk, Verwoerd, & de Vrieze, 2008) refers to individuals’ ability to regulate the content of cognition by keeping desired information active while inhibiting irrelevant or unneeded information (Miyake, Friedman, Emerson, Witzky, & Howerter, 2000). By this account, persistent re-experiencing symptoms in PTSD may stem from deficits in cognitive systems that regulate and inhibit information more generally (e.g., Anderson & Levy, 2009; Joormann, et al., 2010; Verwoerd, et al., 2008). Individuals with relatively poor cognitive control abilities are hypothesized to be more vulnerable to psychopathology after extreme stress because they are less able to regulate intrusive cognitions.

Consistent with this theoretical model, research using non-clinical samples demonstrates that cognitive control performance, particularly on tasks tapping proactive interference control, is associated with re-experiencing symptoms. Proactive interference refers to difficulty remembering recently learned stimuli due to interference from previously learned stimuli. Tasks that tap proactive interference control typically ask participants to remember multiple stimuli, then assess for the intrusion of formerly learned stimuli onto newer learning. A number of studies have assessed proactive interference control and subsequently asked participants to complete a laboratory-based stressor (e.g., viewing a distressing film). In general, these studies find that greater ability to control proactive interference predicts fewer intrusive memories (e.g., performance on the paired-associates task; Verwoerd, Wessel, & de Jong, 2009, Wessel et al., 2008, CVLT-II interference index, Verwoerd, Wessel, de Jong, Nieuwenhuis, & Huntjens, 2011).

Moreover, extant research demonstrates a positive relationship between the ability to deliberately suppress thoughts and performance on working memory capacity (WMC) tasks, which rely on proactive interference control (Bunting, 2006; Friedman & Miyake, 2004; Lustig, May & Hasher, 2001; May, Hasher, & Kane, 1999). In two studies (Brewin & Beaton, 2002; Brewin & Smart, 2005), the authors used an Operation Span (Ospan) task to assess WMC. In the Ospan task, participants are asked to memorize stimuli while simultaneously performing simple math operations. After a series of stimuli and math operations (usually two to six of each) are presented, participants are asked to recall these stimuli in serial order. In each of these studies participants first completed the Ospan task then subsequently monitored occurrences of a selected neutral thought (Brewin & Beaton, 2002) or a negative personally relevant thought (Brewin & Smart, 2005) during a thought suppression task. In both studies, higher WMC as measured by the Ospan was associated with fewer intrusions during and after participants attempted to suppress these thoughts.

Given that PTSD is characterized by frequent intrusive memories, one hypothesis derived from this literature is that frequency of re-experiencing symptoms in individuals with trauma exposure would be associated with poorer WMC performance. Although no studies to date have examined this specific prediction, two published studies have examined WMC in trauma exposed samples. El-Hage, Gaillard, Isingrini, and Belzung (2006) administered an Ospan task to psychiatric inpatients with and without trauma exposure. Results revealed that those with trauma exposure performed more poorly. However, this study did not examine the relationship between cognitive task performance and PTSD symptoms. Schweizer and Dalgleish (2011) administered an alternate WMC task (Reading Span task) to trauma exposed individuals with current or lifetime history of PTSD and a control group with trauma exposure and no history of PTSD. The authors modified this task such that the assessment contained blocks of neutral and threat-relevant sentences. Results revealed that individuals in the PTSD group performed more poorly when distracters were threat-relevant than individuals in the control group. The groups did not differ significantly when distracters were neutral. Thus, to date research suggests that trauma exposure is associated with deficits in cognitive control and that, within individuals with trauma exposure, deficits may be most pronounced for emotionally salient information. These studies do not, however, examine the relationship between cognitive control and PTSD symptom clusters. Because re-experiencing symptoms occur on a continuum within individuals exposed to trauma, continued testing of predictions from these models would necessitate an analytic approach that examines re-experiencing specifically within a sample of individuals exposed to a traumatic event.

The present study sought to evaluate the potential relationship between cognitive control and PTSD re-experiencing symptoms. Using a sample of individuals with a history of trauma exposure, we explored the relationship between PTSD symptom clusters and cognitive control assessed using a WMC task. We assessed and statistically controlled for depression and trait anxiety scores based on evidence that these factors negatively impact regulation of intrusive cognitions and cognitive control processes (e.g. Joorman & Gotlib, 2008; Eysenck, Derakshan, Santos, & Calvo, 2007 ). We hypothesized that WMC performance would predict posttraumatic stress (PTS) symptoms independently of these general distress factors. More specifically, we predicted that the relationship between WMC performance and PTS would be the strongest for re-experiencing symptoms relative to avoidance and hyperarousal symptoms when controlling for trait anxiety and depression.

2. Method

2.1 Participants

Undergraduate students were recruited for participation from the research participant pool at a large university in southern California. Participants were 77 individuals who endorsed having experienced a traumatic event as defined by the DSM-IV criterion A on the Posttraumatic Diagnostic Scale questionnaire (PDS; Foa, Cashman, Jaycox, & Perry, 1997) i. Consistent with prior literature using WMC assessments (e.g., Conway et al., 2005), 5 participants who failed to maintain an 85% math accuracy criterion during the WMC task were removed from data analyses. Racial makeup of the final sample was: 44% Caucasian, 20% Asian, 17% Hispanic/Latino, 15% other or mixed race, and 4% Black. Individuals received course credit for participation. Table 1 presents demographic and clinical characteristics of the sample.

Table 1.

Demographic and Clinical Characteristics

Age 19 (1.6)
Gender - % female 44
Education 13.4 (1.5)
PDS total score 7.7 (9.2)
BDI-II 10.7 (7.9)
STAI-T 39.6 (11.1)
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Note: PDS: Posttraumatic Diagnostic Scale (Foa et al., 1997); BDI-II: Beck Depression Inventory 2nd edition (Beck et al., 1996); STAI-T: Spielberger State-Trait Anxiety Inventory-Trait Version.

2.2 Measures

2.2.1 Self report measures

Posttraumatic stress symptoms were assessed using the PDS. The PDS is a 49-item questionnaire that assesses the individuals’ trauma history and PTSD symptom severity over the past month. Separate sum scores were calculated for items assessing re-experiencing, avoidance, and hyperarousal. General anxiety was assessed using the trait scale of the State Trait Anxiety Inventory (STAI-T; Spielberger, Gorsuch, Lushene, Vagg & Jacobs, 1983). The STAI-T contains 20 items that assess feelings of general trait anxiety. Depression was assessed using the Beck Depression Inventory – II (BDI-II; Beck, Steer, & Brown, 1996). The BDI-II questionnaire contains 21 items assessing depressive symptoms over the previous two weeks. Participants also completed a brief demographic questionnaire to assess age, education level, and ethnicity.

2.2.2 Working Memory Capacity Assessment

WMC was assessed using a computerized Ospan assessment (Unsworth, Heitz, Schrock, & Engle, 2005). Each trial began with a fixation cross in the center of the screen for 500ms. Then, a letter (e.g., L) was presented on the screen for 500ms, followed by a completed math problem (e.g., 1+3 = 6). Half of the equations were correct and half incorrect. The participant was asked to determine whether or not the math solution was correct by selecting a corresponding mouse button (left for “yes,” right for “no”). During the task, the participant’s math accuracy was displayed in the lower left-hand corner of the screen. Once the participant completed the math problem, the next trial began with another letter and equation, until the end of the set. Participants were tested on working memory span sizes from two to six (i.e., saw two to six letters in each set; Engle, Tuholski, Laughlin, & Conway, 1999). At the end of each set participants saw a recall screen listing twelve letters. Using the mouse, participants selected the letters they had seen in serial order of presentation. Three trials of each set size were presented for a total of 15 trials. Once the recall for the set was completed, the next set of trials began in the same manner. Sets and trials were presented in a different random order for each participant. WMC score totals were calculated by summing the number of correctly recalled items in perfectly recalled sets (Schweizer & Dalgleish, 2011)ii.

2.3 Procedure

Upon arrival to the laboratory participants read and signed the study informed consent form. Participants then completed the self-report questionnaire battery containing the demographics questionnaire, PDS, STAI-T, and BDI-II. Participants next began the computer-based WMC assessment by completing a short practice session of the Ospan task. The experimenter read instructions to the participants as they read written instructions on the computer monitor. Participants were instructed to remember the letters presented on the screen while they simultaneously solved the math questions. They were told to make their decision about the accuracy of the math problems as quickly and as accurately as possible. Each participant was instructed to maintain his or her math problem accuracy above 85%. Once the experimenter confirmed that the participant understood all task directions the full-length Ospan was completed.

3. Results

3.1 Correlations between symptom scales and cognitive performance

Table 2 presents correlations between PTS symptom clusters and Ospan performance. Results indicated that Ospan performance was negatively and significantly correlated with re-experiencing symptoms. Correlations between Ospan performance and the avoidance and hyperarousal symptom clusters did not reach statistical significance.

Table 2.

Bivariate correlations between anxiety, depression, PTSD symptom clusters, and Operation Span performance

Measure 1 2 3 4 5 6 7
1. STAI-T 1.00
2. BDI-II .87** 1.0
3. PDS total scores .54** .67** 1.00
4. PDS reexperiencing .39** .52** .93** 1.00
5. PDS avoidance .50** .62** .92** .81** 1.00
6. PTSD hyperarousal .58** .69** .90** .75** .70** 1.00
7. Ospan score .03 −.03 −.19 −.24* −.16 −.09 1.00
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Note. STAI-T: Spielberger State-Trait Anxiety Inventory-Trait Version; BDI-II = Beck Depression Inventory II; PDS = Posttraumatic Diagnostic Scale;

*

p < .05,

**

p < .01.

3.2 Working memory capacity as a predictor of PTSD symptom clusters

Step-wise hierarchical linear regression was used to relationship between WMC performance and PTS symptom clusters. For these analyses WMC performance (Ospan total scores) was used as an independent variable predicting total scores from the PDS re-experiencing, avoidance, and arousal subscales controlling for trait anxiety (STAI-T) and depression (BDI-II). Table 3 presents results from these analyses. Results revealed that inclusion of STAI-T and BDI-II scores accounted for significant variance in the model with re-experiencing symptoms. The addition of Ospan performance explained additional variance in re-experiencing symptom scores. Moreover, WMC and depression both independently predicted re-experiencing symptoms but trait anxiety did not. For the model including avoidance symptoms, including STAI-T and BDI-II scores significantly improved the model. Including Ospan scores did not explain additional variance in avoidance symptom scores. When examining the individual variables, depression independently was associated with symptoms but WMC and trait anxiety did not. Similarly, adding STAI-T and BDI-II scores to the model including hyperarousal symptoms accounted for significant variance but the addition of Ospan scores did not explain additional variance. BDI-II scores but not Ospan performance or trait anxiety independently were associated with hyperarousal symptoms. In summary, when controlling for level of depression and trait anxiety, WMC performance was negatively associated with scores from the re-experiencing subscale of the PDS but not scores from the avoidance or hyperarousal subscales.

Table 3.

Hierarchical regression analyses predicting PTSD symptom clusters and from trait anxiety, depression, and WMC

(a) PDS Re-experiencing (b) PDS Avoidance (c) PDS Hyperarousal
Predictor B SE B β R2 B SE B β ΔR2 B SE B β ΔR2
Step 1 .27*** .39*** .47***
STAI-T −.06 .06 −.22 −.05 .06 −.15 −.02 .06 −.06
BDI-II .28 .08 .70** .34 .09 .75*** .33 .08 .74***
Step 2 .04* .03 .01
STAI-T −.05 .06 −.17 −.04 .06 −.11 −.02 .06 −.05
BDI-II .26 .08 .65** .32 .09 .71*** .32 .08 .72***
Ospan −.05 .02 −.21* −.04 .02 −.17 −.02 .02 −.07
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Note. STAI-T: Spielberger State-Trait Anxiety Inventory-Trait Version; BDI-II: Beck Depression Inventory, 2nd edition (Beck et al., 1996); Ospan: Operation span score.

*

p < .05.

**

p < .01.

***

p < 001

4. Discussion

The present study aimed to test specific predictions outlined in recent theoretical explanations of intrusive memories (e.g., Anderson & Levy, 2009; Joormann et al., 2010; Verwoerd et al., 2008). Specifically, the study examined whether or not poor cognitive control is associated with greater re-experiencing symptoms within a sample of individuals with a history of trauma exposure. Consistent with study hypotheses, results indicated that WMC performance is associated with PTSD re-experiencing symptoms. However, the relationships between WMC performance and avoidance and hyperarousal symptoms did not reach statistical significance.

The present findings add to a growing body of literature indicating that poor cognitive control is implicated in the emergence and regulation of re-experiencing symptoms after stress. These data also extend prior findings in a number of ways. First, the study provides an additional conceptual replication of prior studies (e.g., Verwoerd et al., 2011) using an alternative form of cognitive control assessment. Although two previous studies using WMC tasks (versus specific proactive interference assessments) yielded mixed results (e.g., Nixon, Nehemy, & Seymour, 2007; Wessel et al., 2008 Experiment 1; although see Klein & Boals, 2001), methodological characteristics of the present study may explain this discrepancy. For example, because WMC tasks are complex and require multiple cognitive processes, the relationship between intrusive memories and cognitive control assessed using WMC tasks may be weaker than other forms of assessment (Verwoerd et al., 2011). The relatively large sample and selection of participants with a range of severity of re-experiencing symptoms (compared to unselected participants who typically endorse relatively few intrusive memories) may have augmented the ability to detect this relationship. Second, the study was designed to evaluate the predictions of the model in a sample of individuals with trauma exposure and associated re-experiencing symptoms. This is in contrast to prior studies using stressors experienced within the laboratory setting. These data increase confidence that the phenomenon observed in prior laboratory-based studies extend to clinical symptomatology in the form of re-experiencing PTS symptoms after trauma.

Research examining the link between cognitive control and intrusive memories may yield information with clinical relevance. Recognizing cognitive control as a potential vulnerability factor may improve identification of those most at risk for PTSD. For example, cognitive control assessment might indicate individuals who are vulnerable to PTSD among those likely to experience trauma (e.g., police or first responders) to more efficiently prepare and administer psychosocial interventions. Alternatively, this type of assessment could identify those who would benefit from prophylactic interventions prior to or soon after trauma exposure (e.g., active duty military). Additionally, researchers have proposed that this type of cognitive functioning may be amenable to interventions that directly target cognitive control. Similar to other types of cognitive bias modification training (e.g., attention training; Amir, Beard, Burns, & Bomyea, 2009), targeting cognitive control processes that are etiologically involved in the regulation of intrusive memories may be one pathway to reducing symptoms (Bomyea & Amir, 2011; Schweizer & Dalgleish, in press). Clinical trials of this sort in clinical populations are currently underway (Schweizer & Dalgleish, 2011, Bomyea et al. – see author note for grant information).

Limitations of the present study warrant consideration. The data collected was cross-sectional in nature, precluding conclusions about the causal direction of the relationship (i.e., it is possible that trauma-related re-experiencing symptoms diminish ability to perform on the type of cognitive tasks completed by participants). Although prior studies assessing cognitive control performance prior to laboratory-administered stress argue against this hypothesis, it cannot be ruled out by the present design. The design of the study also required participants to complete potentially anxiety-producing questionnaires prior to doing a cognitive control assessment. Prior research has demonstrated that assessing PTSD symptoms prior to working memory assessments does not impact performance (Jelinek et al., 2008). However, given that anxiety can detrimentally affect cognitive functioning (e.g., Ashcraft & Kirk, 2001), future studies in this area might counterbalance the administration of assessments across participants. The study also utilized a convenience sample of undergraduates and did not diagnose any individuals with PTSD. Research prospectively assessing cognitive control prior to trauma exposure with the addition of diagnostic assessment would provide stronger evidence that cognitive control performance is a pre-trauma vulnerability factor for greater re-experiencing symptoms in clinical samples. In addition, one cannot conclude from the present study that cognitive control is not associated with symptoms falling along the hyperarousal and avoidance dimensions. Rather, the relationship between cognitive control and PTSD symptoms appears strongest for re-experiencing symptoms relative to the other two symptom clusters.

In conclusion, the present study indicates that WMC performance is negatively associated with PTSD re-experiencing symptoms in a sample of individuals who reported a history of trauma. These findings are consistent with prior research positing that cognitive control abilities play a role in regulating the experiencing of intrusive memories and cognitions. Future research is needed to explore clinical implications of these models in terms of prevention and treatment of disorders characterized by intrusive thoughts and memories, such as PTSD.

Highlights.

  • Examined the relationship between cognitive control and PTSD symptoms

  • Cognitive control appears to be specifically associated with re-experiencing symptoms

  • Findings support models implicating cognitive control in memory regulation

Acknowledgments

This work was supported by a grant from the National Institutes of Health awarded to the first (1F31MH088170-01) author. We would like to thank Rachel Lale, Salena McCaslin, and Laura Peterson for their help in data collection for this project.

Footnotes

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i

Participants were selected based on the presence of trauma history from a larger group of participants who completed the self report and cognitive assessments described here. A subset of participants completed a computer-based cognitive training program after the assessments reported here. Details of this subsample are reported in Bomyea and Amir (2011). In addition, data from two participants was lost due to technical error.

ii

Data were also analyzed using total correctly recalled across all sets (Conway et al., 2005). This change did not alter the pattern of results.

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