Measuring Resilience to Operational Stress in Canadian Armed Forces Personnel

Abstract

Adaptability to stress is governed by innate resilience, comprised of complex neuroendocrine and immune mechanisms alongside inherited or learned behavioral traits. Based on their capacity to adapt, some people thrive in stressful situations, whereas others experience maladaptation. In our study, we used state-of-the-art tools to assess the resilience level in individuals, as well as their susceptibility to developing military stress-induced behavioral and cognitive deficits. To address this complex question, we tested Canadian Armed Forces (CAF) personnel in three distinct stress environments (baselines): during predeployment training, deployment in Afghanistan, and readjustment upon return to Canada. Our comprehensive outcome measures included psychometric tests, saliva biomarkers, and computerized cognitive tests that used the Cambridge Neuropsychological Automated Test Battery. Participants were categorized based on initial biomarker measurements as being at low-, moderate-, or high stress-maladaptation risk. Biomarkers showed significant changes (ds = 0.56 to 2.44) between baselines, calculated as "delta" changes. Participants at low stress-maladaptation risk demonstrated minimal changes, whereas those at high stress-maladaptation risk showed significant biomarker variations. The psychometric patterns and cognitive functions were likewise affected across baselines, suggesting that the panel of saliva stress biomarkers could be a useful tool for determining the risk of stress maladaptation that can cause psychological and cognitive decline.

Physiological Factors Which Influence Cognitive Performance in Military Personnel

“…An 8% greater decline over time was observed in deployers compared with non-deployers on a visual reproduction task (Vasterling et al, 2006), and on a paired associates task an 11% greater improvement was recorded in the non-deployers (Vasterling et al, 2006). On tasks of executive function, logical reasoning did not differ over time in deployers compared with non-deployers (Vasterling et al, 2006), while in individuals at a low to moderate risk of stress maladaptation response inhibition improved from baseline to deployment but became impaired in those at high risk (Hellewell & Cernak, 2018).…”

“…Performance was improved, unchanged, and impaired across cognitive domains, with all reported changes marginal. One study specially examined individual characteristics which may predict those more at risk of impaired performance over a period of deployment (Hellewell & Cernak, 2018). This study assessed biological markers of stress including cortisol, testosterone, and α-amylase, as well as parameters of immunity and inflammation.…”

“…Although the effect of these biomarkers on performance will be discussed in the “Biological Factors” section, it may be possible to predict individuals more susceptible to performance decline by examining early signs of stress maladaptation. On tasks of attention and processing speed, simple and choice reaction time was improved by an average of 4% across deployment in one study (Vincent, Roebuck-Spencer, Lopez, et al, 2012), but was impaired or unchanged in another, which evaluated the stress-related biomarkers present just prior to deployment (Hellewell & Cernak, 2018). For simple reaction time, the performance of personnel who exhibited one or fewer stress-related biomarkers was marginally slower during deployment compared with pre-deployment.…”

“…The performance of personnel who exhibited two or more stress-related biomarkers was unchanged. For choice reaction time, all personnel recorded slower reaction time during deployment (Hellewell & Cernak, 2018). For tasks of working memory, performance on a matching to sample (Vincent, Roebuck-Spencer, Lopez, et al, 2012) and spatial working memory task (Hellewell & Cernak, 2018) was improved pre to post deployment, although the magnitude of effect ranged from trivial to small.…”

“…For choice reaction time, all personnel recorded slower reaction time during deployment (Hellewell & Cernak, 2018). For tasks of working memory, performance on a matching to sample (Vincent, Roebuck-Spencer, Lopez, et al, 2012) and spatial working memory task (Hellewell & Cernak, 2018) was improved pre to post deployment, although the magnitude of effect ranged from trivial to small. An 8% greater decline over time was observed in deployers compared with non-deployers on a visual reproduction task (Vasterling et al, 2006), and on a paired associates task an 11% greater improvement was recorded in the non-deployers (Vasterling et al, 2006).…”