Laura Manenschijn, MD, from Erasmus MC, in Rotterdam, the Netherlands, and colleagues wrote, "We found a 2.7-times increased risk of cardiovascular disease in our participants in the highest hair cortisol quartile compared to participants in the lowest quartile."
"This odds ratio [OR] is in the same range as previously described odd ratios of traditional cardiovascular risk factors such as hypertension (OR 2.5) and abdominal obesity (OR 2.2) and is only slightly lower than the increased risk of cardiovascular disease caused by diabetes mellitus (OR 3.1) and dyslipidemia (OR 3.3). This suggests that high long-term cortisol levels might be an important risk factor for cardiovascular disease as well."
The impact of long-term, slightly elevated levels of the "stress hormone" cortisol is unclear, say some researchers who have reported finding an increased risk of CVD, while others found no association or a reverse relationship. But previous work has mostly measured cortisol in serum or saliva, which provides a snapshot at one time. In reality, however, cortisol levels vary over time, fluctuate with circadian rhythm, and are affected by acute stress, they explain.
Reliable, validated tests to measure cortisol in scalp hair have become available in recent years and may provide clues about chronic stress. Since hair grows at the rate of about 1 cm a month, the cortisol in the 1 cm of hair closest to the scalp should reflect stress experienced by the individual over the previous month, they note.
To investigate whether long-term high levels of cortisol were linked with increased risk of CVD, the researchers measured the stress hormone in 283 community-dwelling participants in LASA, who were aged 65 to 85 (66% were women).
They collected about 150 strands of hair from the head of each participant, using the 3 cm of hair closest to the scalp. Cortisol was extracted using methanol and heat, and the samples were analyzed using a commercial ELISA kit for salivary cortisol (DRG Instruments, Marburg, Germany).
Patients reported whether they had any cardiovascular disease — coronary heart disease, peripheral arterial disease, or stroke — or any noncardiovascular disease — lung disease (asthma or chronic obstructive pulmonary disease), diabetes, cancer, or osteoporosis — and whether they smoked or drank alcohol. Their height, weight, and waist circumference were also measured.
Hair cortisol levels were divided into quartiles with the following cutoff points: 16.9 pg/mg, 22.1 pg/mg, and 30.6 pg/mg.
Participants with high long-term cortisol levels were more likely to have a history of CVD, but there was no link with noncardiovascular diseases. Women had lower cortisol levels than men, even after the analyses were repeated in participants who did not dye or bleach their hair, and there was no correlation between hair cortisol levels and age, unlike in previous smaller studies in different age groups.
Previous work [Pereg et al, Stress 2011;14:73-81] found significantly higher levels of cortisol in the hair of men presenting to the emergency for a myocardial infarction, as opposed to men presenting for other reasons — suggesting that there may, in fact, be a causal relationship, the researchers note.
Senior author Elisabeth van Rossum, MD, from Erasmus MC, said in a statement, "The data showed a clear link between chronically elevated cortisol levels and cardiovascular disease." "Additional studies are needed to explore the role of long-term cortisol measurement as a cardiovascular disease predictor and how it can be used to inform new treatment or prevention strategies."
J Clin Endocrinol Metab. Published online April 17, 2013. Abstract