An association between heart rate variability and serum cortisol, dehydroepiandrosterone-sulfate, as an index of stress status and adrenal insufficiency

Background: Heart rate variability (HRV) and its computed components are non-invasive, reliable, and popular indicators for assessing the activities of the autonomic nervous system. They are used for indirect evaluation of not only stress also stress induced adrenal fatigue, which may mean to lower level of the cortisol and dehydroepiandrosterone-sulfate (DHEA-s). In this study, we investigated the associations between HRV parameters and serum cortisol, DHEA-s as an index of stress and adrenal insufficiency. Methods: This study included 281 adult Korean subjects (mean age 54.3±11.9 years) who visited health examination center in the Chaum Life Center from 2010 to 2015. Hormonal analysis included serum levels of cortisol, DHEA-s. HRV parameters were derived from the recordings of device named SA-6000P, performed in 3 minutes at the same condition. Results: In the evaluation of HRV, most of parameters for vitality and ANS (autonomic nerve system) activity (SDNN [standard deviation of all RR intervals], low frequency [LF] and high frequency [HF]) decreased with age (P<0.05). Pearson correlation analysis showed that DHEA-s were positively correlated with LF (P<0.01), total power (TP) (P<0.01) and SDNN (P<0.05). After adjustment by age, sex, smoker, drink and body mass index (BMI), DHEA-s was positively correlated with LF (P<0.01). Low serum cortisol level as an indication of chronic stress was associated with low SDNN and RMSSD (square root of the mean of the sum of the squares of differences between successive RR intervals). As cortisol level was elevating, LF/HF ratio was increasing with statistical significant. Conclusion: Our results demonstrated positive correlations between LF and DHEA-s, independent from age, sex, smoker, drink, BMI. Low SDNN and RMSSD of HRV indicate chronic stress whereas elevated LF/HF ratio indicates acute stress. It suggests that HRV analysis is a reliable method in the assessment of stress status and adrenal fatigue.