Hair samples may provide insight into stress levels preceding myocardial infarction (MI), according to a Canadian study. Although the association between acute stress and MI is well recognised, research into the role of chronic stress has been limited by recall bias and lack of a reliable biological marker. The stress hormone cortisol, which accumulates in hair, may be just such a marker. As hair grows at a rate of about 1 cm per month, the researchers measured cortisol levels in the proximal 3 cm of scalp hair to reflect stress levels in the previous 3 months. The study, claimed to be the first to use hair samples for this purpose, found that median cortisol levels were significantly higher in the 56 MI patients (P = 0.006) compared with controls. On multivariate analysis, hair cortisol levels had a stronger correlation with MI than other risk factors such as body mass index and cholesterol levels (OR, 17.4; 95% CI, 2.15-140.5). Patients with raised hair cortisol levels may therefore benefit from more aggressive management of cardiovascular risk factors.
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