Abstract
Background
Cognitive performance under stress is influenced by neuroendocrine and neurotrophic mechanisms, with brain-derived neurotrophic factor (BDNF) and cortisol playing distinct roles in neuroplasticity and stress adaptation. While BDNF has been primarily linked to memory and neuroplasticity, this study extends its investigation to explore BDNF’s role in inhibitory control and vigilance measures. Specifically, we examine the relationship between serum BDNF-1, cortisol, and cognitive performance under psychosocial and heat stress conditions, with a focus on response inhibition and reaction time.
Aims & Objectives
This study aims to: (1) characterise BDNF and cortisol responses to distinct stressors, (2) assess their associations with cognitive performance, and (3) model the predictive capacity of these biomarkers using Bayesian regression.
Method
Participants underwent both psychosocial (Trier Social Stress Test) and heat stress trials, with serum BDNF and cortisol measured across four timepoints. A subset of 16 participants in the psychosocial trial and 18 participants in the heat stress trial had their serum samples analysed. All biomarker measurements were conducted in duplicate using the Human BDNF-1 ELISA Kit following the manufacturer’s protocol. Cognitive performance was assessed post-stress using the Parametric Go/No-Go task (inhibitory control) and Psychomotor Vigilance Task (PVT). Spearman’s correlation and regression analyses were employed to explore the relationships between baseline BDNF, cortisol, and cognitive outcomes across the two stress conditions.
Results
Changes in BDNF levels differed significantly between stressors, with heat stress inducing an increase and psychosocial stress causing a decrease. These changes were driven primarily by post-stress levels relative to baseline. Baseline BDNF was negatively correlated with inhibitory control in the Go/No-Go task (percentage of correct targets identified in round 3) and positively associated with slower reaction times (PVT) in the psychosocial trial. Similarly, higher baseline cortisol levels were highly correlated with poorer performance in the Go/No-Go task within the psychosocial trial. No significant correlations were found between cortisol and BDNF levels.
Discussion & Conclusions
These findings suggest that higher baseline BDNF and cortisol levels predict poorer attentional control and slower reaction times under stress. The differential regulation of BDNF expression between psychosocial and heat stress underscores the importance of stressor-specific neurobiological pathways in cognitive performance. The use of Bayesian predictive models highlights the capacity of BDNF and cortisol to independently explain cognitive variability under acute stress conditions. Future research should expand on these findings using larger samples and multivariate models to enhance the precision of biomarker-based predictions of cognitive performance. These insights contribute to understanding individual variability in stress resilience and may inform personalised interventions for stress-related cognitive impairments.