The effect of mortality salience and early-life maternal care on neuroendocrine, autonomic, and psychological stress responses

Abstract

Adverse early-life experiences alter the regulation of major stress systems such as the hypothalamic-pituitary-adrenal (HPA) axis. Low early-life maternal care (MC) has repeatedly been related to blunted cortisol stress responses. Likewise, an acutely increased awareness of mortality (mortality salience [MS]) also has been shown to blunt cortisol responses. In this study we investigated the effects of early-life MC and a potential interaction with MS on HPA axis responsivity, as well as autonomic and subjective stress responses. Seventy-three women (M_age=21.56, SD_age=2.85) with self-reported low (n = 30) or high (n = 43) early-life MC, underwent the Trier Social Stress Test for groups. Before, they were asked to briefly contemplate either death (mortality condition, n = 38) or sleep (control condition, n = 35). Salivary cortisol and alpha amylase, heart rate variability and subjective stress levels were assessed repeatedly. Multilevel mixed models confirmed an effect of MC on stress system regulation, indicated by blunted cortisol responses and overall reduced heart rate variability in low versus high MC individuals. Moreover, we found an interaction between MS and MC concerning subjective stress and autonomic measures. Specifically, low MC individuals in the control compared to the mortality condition showed both overall higher subjective stress levels, and less increase in heart rate variability following stress. These findings demonstrate the enduring impact of low early-life MC and the potential role of acute mortality primes on the regulation of stress systems in healthy women.

Keywords: Early-life adversity; HPA axis; Maternal care; Mortality salience; Stress; TSST.

Fig. 1

Changes in cortisol levels (logarithmised) over time in the four groups that vary with regard to MC (low, high) and MS (MS, CS). Values represent means ± SE. There was a significant time by MC interaction: Individuals with low compared with high MC showed reduced cortisol stress responses, indicated by lower cortisol levels during parts of the recovery phase (p = .019). TSST-G = Trier Social Stress Test for groups, MC = maternal care, MS = mortality salience, CS = control stimulus.* p < = 0.05.

Fig. 2

Changes in (a) subjective stress, (b) sAA (root transformed) and (c) RSA levels over time in the four groups that vary with regard to MC (low, high) and MS (MS, CS). Intervention refers to the experimental MS manipulation. Values represent means ± SEs. For subjective stress (a) we found a significant MC by MS interaction: Low MC individuals in the CS compared with the MS condition showed higher subjective stress levels, particularly during the recovery phase (p = .004). For RSA (c) there was a significant main effect of MC: Individuals with low compared with high MC showed an overall lower RSA, particularly during the stress and recovery phase (ps < = 0.039). Significant group differences (in a, c) are marked with an asterisk. MC = maternal care, MS = mortality salience, TSST-G = Trier Social Stress Test for groups, sAA = salivary alpha amylase, RSA = respiratory sinus arrhythmia. * p < = 0.05.

Fig. 3

Study procedure. The experimental manipulation consisted of writing an essay regarding one’s own death (MS condition) or sleep (CS condition). Black boxes represent 5-min intervals for HRV calculation (I₁ to I₁₅). MS = mortality salience, CS = control stimulus, TSST-G = Trier Social Stress Test for groups, HRV = heart rate variability.