Cardiovascular responses to an acute psychological stressor are associated with the cortisol awakening response in individuals with chronic neck pain

Abstract

Introduction: Dysregulation of the hypothalamic-pituitary-adrenal axis (HPA-axis) is common in individuals who experience chronic psychological stress, as well as individuals with chronic pain. Changes in cortisol availability in the presence of a chronic stressor such as pain may influence the sympathetic-adrenal-medullary (SAM) system, which contributes to cardiovascular responses to stress and also exhibits altered responsiveness in the presence of pain. The purpose of this study was to investigate the relationship between HPA activity during the cortisol awakening response and cardiovascular reactivity during exposure to an acute psychological stressor in individuals with chronic neck pain.

Methods: Area under the curve (AUC) of the salivary cortisol awakening response was assessed in 41 individuals with chronic neck pain aged 19-80 years (22 men, 23 women). Slopes representing the change in mean arterial pressure and heart rate during a baseline quiet sitting condition, a low stress condition with mental concentration, and a high stress condition combining mental concentration with social evaluative threat were calculated for each individual as an index of cardiovascular responsiveness to the acute stressor. Cardiovascular responses were regressed on cortisol awakening AUC and pain duration, adjusting for age and sex.

Results: Greater mean arterial pressure (β = -0.33, p = 0.02) and heart rate responses (β = -0.41, p = 0.007) to the acute psychological stressor were associated with lower cortisol awakening responses after adjusting for age and sex. Individuals with a shorter duration of chronic pain also demonstrated a larger increase in mean arterial pressure during the laboratory stressor (β = -0.39, p = 0.01), but there was no relationship between pain duration and changes in heart rate (p = 0.25).

Conclusions: Individuals with a shorter duration of chronic neck pain who demonstrate heightened cardiovascular responsiveness to an acute psychological stressor also exhibit lower cortisol awakening response. These results are consistent with time-dependent adaptations across the two major stress systems in the presence of chronic pain.

Keywords: Cardiovascular; Chronic pain; HPA; Stress.

Figure 1

Mean (SD) salivary cortisol levels upon wakening (AM+0) and every 15 minutes thereafter (AM+15, AM+30, AM+45). The cortisol awakening response (CAR) was measured as the area under the curve for each participant. * p<0.05 compared to AM+0; + p<0.05 compared to AM+15

Figure 2

Individual (grey) and group mean (SD) (black) responses to the acute psychological stressor. On average, mean arterial pressure (A) increased across baseline, low stress, and high stress conditions (p<0.001), whereas heart rate (B) did not (p=0.98). Individual responses to the stressor were measured as the slope of the line across conditions.

Figure 3

Scatter plots showing bivariate associations between cortisol area under the curve (AUC) (x-axis) and pain intensity on the day of testing (A), mean arterial pressure (MAP) slope (B), and heart rate (HR) slope (C) on the y-axes, respectively. Significant beta weights were found between cortisol AUC and cardiovascular responses to the stressor in the adjusted multivariate regression.