Circulating Biomarkers of Military-Specific Performance Resilience: A Systematic Review

Purpose of Review: To systematically examine the available literature on circulating biomarkers of performance resilience in a military environment, with the goal of identifying the most promising circulating biomarkers. Recent Findings: The construct ‘resilience’ is hypothesized to play an important role in increasing Special Operations Forces’ and other military personnel’s capacity for withstanding exposure to various military-specific stressors. However, objectively measuring resilience is challenging. Some of the most important and well-studied circulating biomarkers that affect military-specific resilience are cortisol, dehydroepiandrosterone (sulfate) [DHEA(S)], noradrenaline, serotonin, neuropeptide-Y (NPY) and brain-derived neurotrophic factor. Despite growing evidence, the available knowledge is yet to be summarized and reviewed while considering the intensity and duration of military-specific stressors, military experience, and methodological differences between studies. Summary: Cortisol, Insulin-like growth factor-1 (IGF-1), NPY and DHEA(S) provide a physiological window into military-specific resilience. In general, individuals who exhibit a pronounced but controlled biomarker response to an acute stressor, combined with a quick recovery to baseline, demonstrate physiological flexibility that is associated with greater military-specific resilience. Future research will need to determine relative thresholds for the acute stressor-related change in circulating biomarkers and relative timing to stressor, to correctly interpret ‘a pronounced but controlled biomarker response’ and ‘quick recovery to baseline’.