Covariance between psychological and endocrine responses to pharmacological challenge and psychosocial stress: a question of timing.

OBJECTIVE: To test if the covariance of hypothalamus-pituitary-adrenal (HPA) axis and subjective-psychological responses to stress is dependent on different dynamics of these systems. Although stress theories typically assume substantial correlations of psychological and endocrine stress responses, studies have produced inconsistent results. One reason for this might be imperfect coupling of the different stress response systems. However, inconsistent correlations might also be a result of different on-/offsets of these stress responses, i.e., specific dynamics of the systems.
METHODS: HPA axis indicators and subjective-psychological states were repeatedly and synchronously measured in a pharmacological challenge test (injection of corticotropin-releasing hormone and infusion of arginine vasopressin; Study 1; n = 42) and a psychosocial stress situation (Trier Social Stress Test; Study 2; n = 219). Cross-correlation analysis was used to test for lag effects in HPA axis reactivity and psychoendocrine responses.
RESULTS: Analyses revealed high cross-correlations of adrenocorticotropic hormone with cortisol responses (up to r = .80 in Study 1 and r = .56 in Study 2) and positive associations of psychological with endocrine stress responses (up to r = .48 in Study 1 and r = .54 in Study 2) at nonzero lags. Subjective-psychological responses preceded HPA axis responses. Moreover, high levels of cortisol were associated with lower later levels of anxiety and activation.
CONCLUSIONS: The findings suggest that psychoendocrine stress responses are more closely coupled than previous studies suggested. Due to different dynamics of the systems, endocrine responses lag behind psychological responses.