Hair Cortisol and the Risk of Stroke

Acute physical and emotional stressors are well known triggers of cardiovascular events. However, it is not clear whether the same association exists with chronic stress. Data on this issue have been limited by lack of adequate clinical studies and inconclusive results. One of the possible explanations may be the absence of a reliable mode for quantitative assessment of chronic stress. To date, studies on the effects of chronic stress on cardiovascular events have used psychosocial questionnaires. These are subject to recall bias, as having an event may stimulate the patient to strive harder to identify previous stressors. Furthermore, most studies on the association of chronic stress and cardiovascular events have focused on acute coronary events, and only few have examined the association with stroke.

Both physical and emotional stress activate several neuroendocrine systems, the most important being the hypothalamic-pituitary-adrenal (HPA) 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 presenting with acute myocardial infarction and stroke compared to healthy controls. Moreover, it has been shown that serum cortisol levels correlates with the severity of the disease and adverse outcome in patients presenting with stroke.

Cortisol levels are routinely determined from blood, salivary or urinary samples. However, these methods do not provide information on long term cortisol secretion, accounting for the variability of HPA axis activity. There is a growing pool of evidence that shows that Hair Cortisol Concentration (HCC) examination provides a reliable retrospective estimation of integrated cortisol secretion over a period of several months. Hair grows at a rate of about 1 cm/month, thus 3 cm of hair would give an indication of the cortisol levels over the previous 3 months. HCC has been evaluated in several clinical settings in which activity of the HPA axis and cortisol levels over a period of time are of interest. Studies have demonstrated increased levels of hair cortisol in chronic stress, as well as conditions associated with stress such as pregnancy , unemployment , PTSD, alcohol withdrawal and chronic pain and more importantly, in patients admitted to hospital with acute myocardial infarction. Nevertheless, the association between hair cortisol levels and the risk for stroke has not yet been studied.