Activities of the hypothalamo-pituitary-adrenal axis and autonomic nervous system following a strong earthquake.

Abstract

This study aimed to investigate the effects of post-traumatic stress, caused by a strong earthquake, on the hypothalamo-pituitary-adrenal axis (HPA) and autonomous nervous system activity (ANS). Activities of the HPA (as salivary cortisol) and ANS (as heart-rate variability [HRV]) were measured following the 2020 Elazig (Türkiye) earthquake (6.8 Richter Scale, classified as strong). A total of 227 participants (103 men (45%) and 124 women (%55)) provided saliva samples twice, namely, 1week and 6weeks after the earthquake. Of these participants, HRV was measured in 51 participants by 5min continuous electrocardiogram (ECG) recording. Frequency- and time-domain parameters of the HRV were calculated to assess the activity of ANS and low/high frequency (LF/HF) ratio was used as surrogate for sympathovagal balance. Salivary cortisol levels decreased from week 1 towards week 6 (17.40±1.48 and 15.32±1.37ng/mL, respectively, p<0.05). There were no gender differences (17.99±2.63 and 16.90±1.60ng/mL, respectively for females and males, p>0.05) for salivary cortisol levels. There were no differences in time- and frequency domain parameters of the HRV including LF/HF ratio (2.95±0.38 ms2 and 3.60±0.70 ms2 , respectively for week 1 and 6, p>0.05). The data show that HPA axis activity, but not that of the ANS, remains higher 1week after the earthquake but decreases afterwards towards the sixth week, suggesting that the HPA axis might be responsible for the long-term effects of a traumatic event like a strong earthquake.