Hair Cortisol and the Risk of Acute Myocardial Infarction

Acute physical stressors such as surgery, trauma and intense physical exertion are well-known triggers of cardiovascular events. The connection between acute emotional stress and the heart has been controversial for many years. However, emotional stressors are now increasingly recognized as precipitants of cardiovascular events including myocardial infarction (MI). For example, on the day of the Los Angeles earthquake in 1994 the number of cardiac deaths and hospital admissions for acute myocardial infarction was 2-5 times higher than the usual rate. Furthermore, the risk of myocardial infarction in the short period following an acute emotional stress such as anger outburst, seems to be twice that of other periods and may be a more common precipitant than physical exertion1. While the association between acute stress and cardiovascular mortality and morbidity is well established, controversy still exists whether there is the same association with chronic stress, both physical and emotional. Data regarding this question are extremely limited since there has been no objective and reliable mode for the assessment of physical stress and for the quantification of overall chronic stress. Furthermore, the fact that all the information regarding the association between chronic stress and acute MI derives from retrospective studies further complicates this issue.

Both physical and emotional stress activate several neuroendocrine systems, the most important being the hypothalamic-pituitary-adrenal axis that stimulates the production and secretion of glucocorticoids (especially cortisol) from the adrenal cortex. Therefore, cortisol is considered to be a "stress hormone" and higher levels of serum cortisol have been observed in patients with acute stress such as those presented with acute MI, compared to healthy controls.

Currently, there are several modalities for measuring cortisol levels including serum, urinary and salivary techniques. However, all these methods represent indicators of acute stress and do not reflect accumulation of stress over time.

Recently there has been a growing interest in measuring hair cortisol level. Hair grows approximately 1 centimeter per month, and hair analysis accurately reflects long-term endogenous production of cortisol. This provides for the first time a reliable mode for the measurement of the accumulation of cortisol over time and a potential biomarker of chronic stress. Indeed, several reports have demonstrated an association between high hair cortisol levels and chronic stress in both animal models and in humans. Nevertheless, the possible association between hair cortisol and the risk of acute MI has not been studied yet.

Aim of the study: