Prior research suggests that executive function (EF), a group of mental processes (inhibition, working memory, and cognitive flexibility) necessary for concentration and attention, may be an important neurocognitive factor in both risk for, and development of, Posttraumatic Stress Disorder (PTSD). Individuals with PTSD experience deficits in multiple components of EF including working memory, sustaining vigilance and attention, and response inhibition (Vasterling et al., 2009; Martínez et al., 2016; Jacob et al., 2019; Scott et al., 2020). One extant hypothesis is that deficits in EF may represent a neurocognitive subtype of PTSD, possibly influenced by factors such as trauma type or age of trauma exposure (Scott et al., 2015; Jagger-Rickels et al., 2021). Others suggest that disrupted EF is a vulnerability factor for the development or worsening of PTSD symptom severity (Aupperle et al., 2012; Jacob et al., 2019; Scott et al., 2020). Importantly, there is growing evidence that EF can be targeted and improved through physical activity interventions (Sung et al., 2021), cognitive and social rehabilitation training (Novakovic-Agopian et al., 2018; McCarron et al., 2019; Maruyama et al., 2021), and mindfulness-based interventions (Poissant et al., 2020). Given that EF is a potentially malleable risk factor for the development and/or severity of PTSD symptoms, it may be an important target for improving resilience to trauma exposure. However, more research is needed to understand if and how EF influences the relation between trauma exposure and PTSD symptom severity. Using data from the Marine Resiliency Study, a prospective, longitudinal study of PTSD in Active-Duty Marines and Navy Corpsmen, we tested the hypothesis that EF modulates PTSD risk and symptom development after trauma exposure.

In addition to current uncertainty about the role of EF in risk for, and development of PTSD, questions remain regarding the relative impact of different forms of trauma exposure on PTSD symptoms (Kessler et al., 2017; Guina et al., 2018). One large, multi-country survey study found that risk for PTSD increased after trauma exposure, but that the relative risk varied significantly by trauma type, with interpersonally violent traumas carrying the highest level of risk (Kessler et al., 2017). Another study of mental health outpatients found that combat and sexual trauma were associated with greatest PTSD severity, compared to other types such as physical assault or witnessing violence (Guina et al., 2018). These results mirror results of Jakob et al. in a sample of Veterans (Jakob et al., 2017). Similarly, Sheriff and colleagues found that experience of any interpersonal trauma (such as sexual assault or stalking) was significantly linked to meeting the diagnostic criteria for PTSD within the past year, in a sample of military employed as well as in a sample of civilian men. The association between the experience of any non-interpersonal trauma (such as car accidents or major natural disasters) and PTSD was not statistically significant in either cohort (Sheriff et al., 2019). In contrast, Reger et al. (2019) reported that interpersonally traumatic events did not explain mental health outcomes (depression, anxiety, and PTSD symptoms) above and beyond non-interpersonally traumatic events in their sample of active-duty soldiers.

With the goal of improving understanding of EF as a potential antecedent or protective factor for the development of PTSD among military personnel, the current study tested the hypothesis that higher pre-deployment EF promoted better mental health outcomes among a cohort of U.S. Marines. We tested this hypothesis in two ways. First, we used a cross-sectional design to test whether higher EF was directly associated with less severe PTSD symptoms (a main/promotive effect) at the pre-deployment time point. We then tested whether EF moderated (i.e., mitigated) the association between different types of trauma exposure (cumulative lifetime trauma exposure, lifetime direct trauma exposure, and lifetime interpersonal trauma exposure) and PTSD symptom severity at pre-deployment (an interaction/protective effect). Second, we used a longitudinal design to test the hypothesis that greater pre-deployment EF would be associated with fewer PTSD symptoms at post deployment, and that EF would moderate (buffer) the relation between more intense combat experience and greater PTSD symptoms post-deployment.

Table 2 displays means and bivariate associations of study variables. EF was negatively associated with direct and interpersonal life events exposure (p < 0.05), as well as pre- and post-deployment CAPS scores (p < 0.05). Life events cumulative, direct, and interpersonal exposure were all significantly positively correlated with both pre- and post-deployment CAPS scores (p < 0.01). Total combat experience exposure was only associated with CAPS score post-deployment (p < 0.01), in the positive direction. Number of years in the military, alcohol use, traumatic brain injury, and being a non-commissioned officer (only for time 2 posttraumatic stress) were significantly associated with posttraumatic stress and included as covariates in subsequent models.

The results of this study suggest that EF plays a significant, if modest role in the development of PTSD symptoms after trauma exposure. Specifically, in a large cohort of U.S. Marines, we found that higher EF was associated with less posttraumatic stress symptom severity both at pre-deployment and post-deployment. These relations were significant even when adjusting for trauma exposure, alcohol use, traumatic brain injury, and number of years in the military. Further, supplemental analyses demonstrate that these findings are unique to EF and do not extend to other aspects of neurocognition, such as complex reasoning and memory (see Supplementary Tables S3–S10). We also found support for our prediction that EF would moderate the link between trauma exposure and PTSD symptoms, with effects being greatest in regard to cumulative lifetime trauma exposure and interpersonal trauma exposure. Specifically, the expected increase in PTSD symptoms for Marines and accompanying Navy personnel with high versus low cumulative trauma exposure was 20% greater for those with low EF, compared to those with high EF. For service members with high versus low interpersonal trauma exposure, higher EF was associated with a 33% reduction in expected point increase compared to those with low EF. The interaction of EF and direct lifetime trauma exposure, while not significant (p < 0.14), was in the same direction as the effect of EF X other forms of trauma exposure. Finally, higher pre-deployment EF was associated with reduced posttraumatic stress severity at post-deployment, independent of deployment-related trauma exposure. Taken together, these findings suggest that higher levels of EF are linked to less severe PTSD symptoms, adding to existing literature showing that impaired cognitive functioning, including elements of EF, is a significant and independent risk factor for PTSD in trauma exposed individuals (Olff et al., 2014; Schultebraucks et al., 2021; Mathew et al., 2022).

In our study, when examining the impact of EF on the relation between lifetime trauma exposure and PTSD symptoms, we see evidence that its protective effect is greater for those with higher levels of trauma exposure. Evidence from developmental research suggests that the various components of EF begin to develop in the first few years of life, strengthen significantly throughout childhood and early adolescence, and reach stability by late adolescence (Best and Miller, 2010; Friedman et al., 2016). Given the shared neural circuity of EF and PTSD and importance of developmental timing to EF, it may be that trauma exposure in childhood and adolescence has a strong disruptive impact on developing EF. In turn, lower EF is a vulnerability factor for the development of subsequent PTSD symptoms. In support of this hypothesis, one recent systematic review and meta-analysis found that among children with traumatic experiences with and without PTSS, those with PTSS had significantly lower EF (Nyvold et al., 2022).

When solely examining the protective impact of EF in the context of deployment-related trauma exposure and PTSD symptoms, the magnitude of effect remains constant regardless of severity of trauma exposure. More research is needed to understand these findings, but one hypothesis is that the severity or recency of combat exposure, regardless of amount, is enough that the buffering effect of EF is equivalent across all levels.

The EF measure employed in this study was composed of tasks measuring both working memory (WM) and attention. WM impairments in PTSD are well-documented and have been associated with altered neural function in the fronto-parietal central executive network (Patel et al., 2012). These impairments are thought to reflect a decreased ability to filter threatening information out of memory, while also increasing the storage of task-irrelevant threatening distractors (Stout et al., 2013, 2015). This imbalance in the filtering and retention of threat information may result in an increased occurrence of threat-related cognitions characteristic of re-experiencing symptoms, a core symptom of PTSD. PTSD has also been associated with impaired WM in emotional situations, potentially leading to impaired interpersonal and occupational function (Schweizer and Dalgleish, 2011). Impairments in attentional processes are also well-documented in PTSD (Bar-Haim et al., 2007). Diminished response inhibition ability, which is particularly relevant to the attentional tasks used here, are the CPT and Go-No-Go, as well as difficulties disengaging attention from stimuli perceived as threatening (Aupperle et al., 2012) These difficulties may contribute to PTSD symptoms across a number of domains, such as hyperarousal/vigilance, intrusive memories, and lowered ability to focus on tasks.

There are several limitations for consideration when interpreting our study findings. Although we utilize data from two timepoints (pre- and post-deployment), there is also an important focus on trauma exposure in childhood and adolescence that relies on retrospective report. Future prospective studies examining the impact of trauma on development of PTSD and EF, with more specificity as to exact ages/developmental periods of exposure, could add important supporting evidence to the findings of this study. The racial/ethnic distribution of this participant sample (88% white) differed from that of the entire Marine Corps in 2008 (77% white among E1-E9, 82% white among officers O1–O10; Department of Defense Office of Diversity Management and Equal Opportunity, (2023); future research should examine these constructs in more diverse samples. Last, it is important to note that our findings are correlational in nature, and therefore it is impossible to assert true causality between the main constructs under study (EF, trauma exposure, PTSD symptoms).

Despite this study’s limitations, its results provide important considerations for future research and intervention and prevention. First, results provide evidence as to the feasibility of utilizing the WebCNB, and specifically the Continuous Performance Test, Short Letter-N-Back Test, and GO-NO-GO test, to assess EF among male marines. Results of analyses utilizing the EF component versus the EF composite scores closely aligned, suggesting the utility of a mean composite score approach for future research and clinical practice. Study results also highlight the importance of approaches to PTSD intervention and prevention being developmentally informed. Specifically, intervention for youth and adolescents exposed to trauma may want to incorporate a focus not only on addressing core symptoms of posttraumatic stress but also training to improve EF. For adults, for example Marines and accompanying Navy personnel preparing for deployment, exercises to improve EF prior to deployment may be protective against the later development of PTSD symptoms after trauma exposure. There is a growing body of literature documenting various ways to improve EF, including through physical activity (Sung et al., 2021), cognitive and social rehabilitation training (Novakovic-Agopian et al., 2018; Jak et al., 2019; McCarron et al., 2019; Maruyama et al., 2021; Lindamer et al., 2022), and mindfulness (Poissant et al., 2020).

Importantly, some studies suggest that EF may impact certain symptom clusters of PTSD more than others, although these findings are not consistent. For example, Mathew and colleagues found that performance on visuospatial working memory tasks was a significant predictor only of the re-experiencing PTSD symptom cluster (Mathew et al., 2022), while Olff and colleagues reported that EF performance was significantly linked to numbing and avoidance symptom clusters, and not reexperiencing or hyperarousal (Olff et al., 2014). Overall, literature shows a strong relation between EF and PTSD, but an important question for further research is to disentangle the complex relations between the individual components of both EF and PTSD.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by the Veteran’s Administration San Diego Healthcare System, the University of California San Diego, and the Naval Health Research Center. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

TM, RG, CN, DB, and VR participated in study design. SL, TM, CN, and DA conducted the statistical analyses. SL led manuscript preparation and TM, CN, DB, VR, and DA contributed. All authors contributed to the article and approved the submitted version.

Support for this work includes NIMH P50MH096889 (Drs Baker and Risbrough), a VA Career Scientist award, VA Merit Award and NIH R01AA026560 (Risbrough), project No. SDR 09-0128 from the Veterans Administration 615 Health Service Research and Development, the US Marine Corps and Navy Bureau of Medicine and Surgery (Drs Baker, Risbrough, Moore and Gur), the Center of Excellence for Stress and Mental Health (Acheson, Nievergelt, Risbrough, Baker). The project described was also supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1 625 TR001414.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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