Individual differences in biophysiological toughness: sustaining working memory during physical exhaustion

Area of Science:

• Endocrinology
• Military Medicine
• Cognitive Neuroscience

Background:

• Elevated dehydroepiandrosterone sulfate (DHEAS) and reduced cortisol have been linked to improved performance in stressful military settings.
• Understanding these hormonal biomarkers is crucial for optimizing training and operational readiness.

Purpose of the Study:

• To replicate findings on DHEAS and cortisol as performance biomarkers in active duty Air Force members.
• To investigate the relationship between these hormones and cognitive performance under physical stress.

Main Methods:

• Seventeen active duty males underwent cognitive testing and physiological measurements.
• A modified Astrand treadmill protocol induced physical exhaustion, with blood draws for biomarker analysis.
• Cognitive function (working memory, psychomotor vigilance) was assessed before, during, and after the stressor.

Main Results:

• Prolonged increases in cortisol levels were negatively correlated with working memory performance.
• The release of DHEAS post-stress showed a negative relationship with concurrent cortisol changes.
• The ratio of DHEAS to cortisol appeared to mitigate the negative impact of cortisol on working memory.

Conclusions:

• The findings support the role of DHEAS and cortisol as potential biomarkers in military environments.
• The DHEAS/cortisol ratio may serve a protective function against stress-induced cognitive deficits.
• Further research can explore the application of these biomarkers in military personnel management and performance enhancement.