The relationship between chronic stress, hair cortisol and hypertension

Abstract

Inconsistencies in studies of chronic psychosocial stress and hypertension may be explained by the use of stress markers greatly influenced by circadian rhythm and transient stressors. We assessed whether hair cortisol, a marker that captures systemic cortisol over months, was independently associated with hypertension. We measured hair cortisol and blood pressure in 75 consecutive participants in the Survey of the Health of Wisconsin, using an ELISA test. Individuals with values ​≥ ​median (78.1 ​pg/mg) were considered exposed. We used approximate Bayesian logistic regression, with a prior odds ratio of 1.0-4.0, to quantify the multivariate-adjusted hair cortisol-hypertension association. Participants' average age was 46.9 years; 37.3% were male; and 25.3% were hypertensive. Hypertension prevalence was 2.23 times higher in exposed (95% CI: 1.69-3.03). This finding was unlikely explained by differential measurement errors, since we conducted blinded measurements of exposure and outcome. Sensitivity analyses showed the association was unlikely explained by an unmeasured confounder, survival bias, or reverse causality bias. Findings suggest elevated hair cortisol is a risk factor for hypertension. Although feasible, the clinical value of hair cortisol as a tool for hypertension risk stratification or for monitoring the effect of chronic psychosocial stress management interventions is still uncertain.

Keywords: Blood pressure; Chronic psychosocial stress; Cortisol; Hair cortisol; Hypertension.

Fig. 1

A causal DAG representing the relationship between hair cortisol and hypertension. Variables enclosed in circle are those in the minimally sufficient adjustment set (MSAS) of variables that would allow identifying an unconfounded effect of hair cortisol levels on hypertension.

Fig. 2

Area above the line corresponds to the joint values of the (unmeasured) confounder-exposure and confounder-outcome risk ratios that would make the lower limit of the 95% credible interval <1 and explain away the effect of hair cortisol on hypertension.