Abstract:

Recently, An increasing number of studies are focusing on individual differences in response to acute psychological stress. Emerging evidence suggests that personality, especially trait anxiety, might be a significant predictive factor of individual difference in response to acute stress. Most of the previous studies have taken trait anxiety as a categorical (discontinuous)construct. However, a full-range analysis of trait anxiety could result in greater statistical power and less parameter estimation bias. The present study aims to examine whether and how the continuum of trait anxiety scores predict the acute psychological stress response induced by a standardized laboratory stress induction procedure (the Trier Social Stress Test, TSST) while controlling for the potentially confounding factors of gender, age and education years.
A total of 54 healthy students (35 males, 19 females), aged 18~25 years (mean: 22.57 ± 1.67) and educated for 13~18 years (mean: 15.89 ± 1.34), were recruited from universities in Beijing. Several inclusion criteria were employed to control for potential factors influencing the stress response (see 2.1 for details). The acute psychological stress was induced by the TSST and the stress response was measured with heart rate (the index of the response in sympathetic adrenal medulla) and salivary cortisol (the index of the response in hypothalamus pituitary-adrenal). Two hierarchical multiple regression analyses were utilized to study how trait anxiety predicts the heart rate and salivary cortisol response toward stress.
The result showed that the TSST elicited significantly acute psychological stress responses. Specifically, both heart rate and salivary cortisol during the TSST were higher than that measured at any other time points. Regression analysis corroborated that after controlling for gender, age and education years, trait anxiety significantly and negatively predicted heart rate response (β = -0.35, p < 0.01), but not salivary cortisol response to acute psychological stress.
The present findings suggest that trait anxiety is a powerful predictor of sympathetic adrenal medulla response, i.e., individuals with higher level of trait anxiety perform lower sympathetic nerve activity in rapid response to acute psychological stress. Individuals with high trait anxiety may experience long-term anxiety in their daily life and chronic consumption of psychophysiological resources, thereby resulting in the limited response to acute stressors.

Key words: trait anxiety, acute psychological stress, heart rate, salivary cortisol, predict