HPA-axis and inflammatory reactivity to acute stress is related with basal HPA-axis activity.
Level 4 - case-series / case-control
Observational cross-sectional association study in healthy participants
PubMed 28209543 · doi:10.1016/j.psyneuen.2017.01.035
What was done
Forty-eight healthy individuals collected saliva at six time points across the day to assess basal hypothalamic-pituitary-adrenal (HPA) axis activity, including the cortisol awakening response (CAR) and diurnal slope. Participants were exposed to the Trier Social Stress Test (TSST) on two consecutive days. Salivary cortisol and plasma interleukin-6 (IL-6) reactivity and habituation to acute stress were measured and correlated with basal HPA axis measures.
What was found
A steeper CAR linear increase was related to stronger cortisol stress reactivity (gamma = 0.015; p = 0.042) and marginally with greater habituation (gamma = 0.01; p = 0.066). Greater CAR curvilinearity was related to stronger cortisol reactivity (gamma = -0.014; p = 0.021) and greater cortisol habituation (gamma = -0.011; p = 0.006). A steeper daily linear decline was related to stronger IL-6 reactivity (gamma = -0.028; p = 0.031), marginally stronger cortisol reactivity (gamma = -0.0004; p = 0.06), and greater habituation for both cortisol (gamma = -0.002; p = 0.009) and IL-6 (gamma = -0.015; p = 0.033). Greater curvilinearity of daily decline was related to stronger IL-6 reactivity (gamma = 0.002; p = 0.024) and greater habituation for both cortisol (gamma = 0.00009; p = 0.03) and IL-6 (gamma = 0.001; p = 0.024).
Why it matters
The study shows that basal diurnal cortisol patterns typical of healthy regulation are associated with robust initial endocrine and inflammatory stress reactivity coupled with efficient habituation to repeated stress.
Limits
The sample size was small (n = 48) and limited to healthy volunteers. The cross-sectional, correlational design cannot determine causality or the temporal sequence between basal regulation and stress reactivity. Demographic characteristics, exact timing, and unmeasured confounders were not detailed in the abstract.
Cited by
- contradicts A higher peak in the cortisol awakening response in the morning reduces or blunts the magnitude of cortisol spikes caused by stressful events later in the day.