Sex-differences And Changes In Psychophysiological Stress And Resilience During Military Training

Individuals undergoing initial military training are exposed to multi-stressor environments that may impact physiological hormones and psychological indicators of the stress response. PURPOSE: Compare baseline measures of stress and resilience between completers (C) and non-completers (NC) of Marine Corps Officer Candidates School (OCS) and examine changes in males and females who complete OCS. METHODS: 1006 candidates (24.8 ± 3.1 yrs; 22.0 ± 2.4 kg/m2; 20.5% female) completed a saliva collection, blood draw, Perceived Stress Scale (PSS), and Connor-Davidson Resilience (CD-RISC) scale at the start and end of OCS. Salivary cortisol (SaCORT), testosterone (TEST), α-amylase (AMY) and serum cortisol (SeCORT) and dehydroepiandrosterone (DHEA) concentrations were analyzed using enzyme-linked immunoassays. Baseline measures were compared between C and NC using independent samples t tests. Two-way ANOVAs (time*sex) were performed for each dependent variable; α = 0.05. RESULTS: SaCORT, TEST, AMY, and CD-RISC were not different between C and NC (p = 0.086-0.826). PSS (14.1 ± 6.1; 11.4 ± 5.9, p < 0.001) and SeCORT (11.4 ± 4.7 μg/dL; 10.7 ± 4.2 μg/dL, p = 0.038) were higher in NC vs. C. DHEA was lower in NC vs. C (3.9 ± 2.0 ng/mL; 4.3 ± 2.0 ng/mL, p = 0.031). There were no significant interaction or main effects for SaCORT or AMY. A main effect of sex indicated that TEST was greater in males than females (137.5 ± 5.6 pg/mL, 64.1 ± 7.8 pg/mL, p < 0.001). Significant interaction effects on CD-RISC, SeCORT, and DHEA were present (all p < 0.05). In males, CD-RISC did not change over time (82.4 ± 10 to 82.5 ± 9.6, p = 0.904), while females decreased (84.3 ± 6.8 to 80.9 ± 10.2, p = 0.014). SeCORT and DHEA decreased in both sexes but moreso in females (SeCORT: m: 10.7 ± 3.8 to 9.6 ± 3.9 μg/dL; f: 11.1 ± 4.8 to 7.9 ± 3.2 μg/dL, both p < 0.001; DHEA: m: 4.3 ± 1.9 to 3.6 ± 1.6 ng/mL; f: 4.7 ± 2.4 to 3.5 ± 2.0 ng/mL, both p < 0.001). Main effects of time and sex indicated that PSS increased over time (11.9 ± 0.5 to 16.7 ± 0.5, p < 0.001) and females scored higher than males (16.2 ± 0.6, 12.4 ± 0.5, p < 0.001). CONCLUSIONS: Candidates’ subjective feelings of stress increased while physiological indicators decreased following OCS. Decreases in stress hormones and resilience were increasingly evident among females, indicating that changes in stress responses may be sex dependent. Supported by ONR N000142112725