Cortisol and heart health: what long-term cortisol studies show

Cortisol and the heart are closely connected. Cortisol affects blood vessel tone, blood sugar and how the body handles fat,¹ and when it is very high for a long time, as in untreated Cushing's syndrome, the risk of high blood pressure, type 2 diabetes, heart attack and stroke goes up.² In the general population, studies that measure long-term cortisol in hair have found that people with heart disease tend to have higher levels, a pattern confirmed by a 2024 meta-analysis of eight studies.³ But most of this research looks at people at a single point in time, so it shows an association, not that cortisol causes heart disease. And the one large study that followed people forward reported its main finding for hair cortisone, a closely related hormone, not for cortisol.⁴

How cortisol affects the heart and blood vessels

Cortisol is the body's main glucocorticoid hormone. It raises the amount of sugar available in the blood, breaks down protein and fat, affects the immune system and helps set the tone of blood vessels.¹ Those effects are useful in short bursts. A sustained excess causes fat to build up around the middle, muscle wasting, high blood pressure and glucose intolerance,¹ a pattern that overlaps with familiar risk factors for heart disease.

The clearest example is Cushing's syndrome. Untreated, it raises the risk of heart attack, stroke, high blood pressure, type 2 diabetes and blood clots.² In Danish national data, people with non-cancerous Cushing's syndrome died at 3.68 times the expected rate.⁵ Those are the effects of a large, prolonged excess; see high cortisol symptoms for the signs. The question for everyone else is whether more ordinary differences in long-term cortisol matter for the heart.

Why single cortisol tests gave mixed answers

Studies that measured cortisol in a single blood or saliva sample gave inconclusive results on heart disease.⁶ A single sample captures a moment: cortisol peaks at around 8.30 in the morning and falls to its lowest near midnight,⁷ and it rises with stress, exercise and even having blood taken, which triggers a response in about 30 to 47 per cent of people.⁸ In obesity research, authors have suggested that inconsistent results from blood, saliva and urine may reflect how variable cortisol is,⁹ and a 2024 review noted that spot cortisol does not correlate with body mass index, whereas hair cortisol does.¹⁰ Hair gives a measure of exposure over months, which is closer to the kind of sustained exposure that might matter for the heart.

What hair cortisol studies of heart disease found

• Older adults. In 283 community-dwelling people with a median age of 75, those with high hair cortisol were more likely to have a history of cardiovascular disease (odds ratio 2.7) and type 2 diabetes (odds ratio 3.2). There was no link with diseases outside the cardiovascular system.⁶
• Heart attack. In 56 men admitted with a heart attack and 56 men in hospital for other reasons, median hair cortisol in the 3 cm nearest the scalp was 295.3 against 224.9 ng/g. After adjustment for other factors, hair cortisol was the strongest predictor of having had a heart attack (odds ratio 17.4), though the very wide uncertainty range, 2.15 to 140.5, reflects how small the study was.¹¹
• Meta-analysis. Pooling eight studies, a 2024 systematic review found people with cardiovascular disease had higher hair cortisol than people without, with a standardised mean difference of 0.48 (95% CI 0.16 to 0.79).³
• Following people forward. The Lifelines cohort analysed 6,341 hair samples, with hair cortisone available in 4,701, and followed people for 5 to 7 years. Hair cortisone independently predicted new cardiovascular disease, particularly in younger people (odds ratio 4.21 per 10-log unit, 95% CI 1.91 to 9.07).⁴

The cross-sectional studies point the same way, and the Lifelines result suggests long-term glucocorticoid exposure may come before heart disease rather than only after it. But the abstract reports that result for cortisone, which laboratories can measure in the same hair sample, not for cortisol itself.⁴

Metabolic syndrome, weight and blood pressure

Metabolic syndrome is the name for a cluster of heart-risk factors that tend to occur together, such as a large waist, raised blood pressure, raised blood sugar and abnormal blood fats. In 1,258 employees, compared with people in the lowest quarter of hair cortisol, the odds of metabolic syndrome were 1.71 times higher in the third quarter and 2.42 times higher in the top quarter. Hair cortisol was also linked with body mass index, waist measurements and HbA1c, a marker of average blood sugar.¹² However, the 2024 meta-analysis found the links between hair cortisol and metabolic syndrome inconsistent across studies.³

For blood pressure, a 2017 meta-analysis of 66 hair cortisol studies found a positive association with systolic blood pressure (the top number), as well as with body mass index and waist-to-hip ratio.¹³ Links with weight are consistent but small: across 26,527 people, the pooled correlation between hair cortisol and body mass index was r = 0.10.¹⁴ See cortisol and weight for more.

Association is not cause

It is tempting to read these studies as proof that stress hormones cause heart disease, but they cannot show that yet:

• Most are cross-sectional. They measure cortisol and heart disease at the same time, so they cannot say which came first. Illness itself raises cortisol: in critically ill patients, cortisol production was 83 per cent higher than in healthy people.¹⁵
• Other factors travel together. In the Whitehall II study, higher hair cortisol went with diabetes, use of steroid and heart medicines, and depressive symptoms,¹⁶ any of which could muddy a link with heart disease.
• The effect on weight is small. A correlation of r = 0.10 means hair cortisol accounts for only a tiny share of the differences in body mass index between people.¹⁴
• The prospective evidence is for cortisone. The main study that followed people forward reported its finding for hair cortisone.⁴

The trials of lowering cortisol have measured cortisol and risk markers, not heart attacks or strokes. In a year-long trial, 150 minutes a week of aerobic exercise lowered hair cortisol compared with a control group, but other stress and cardiovascular markers did not change consistently.¹⁷ A meta-analysis of 45 trials found meditation lowered cortisol, blood pressure, heart rate, triglycerides and markers of inflammation compared with active control activities,¹⁸ which is encouraging but does not show that the change in cortisol is what helps. Our guide to cortisol and stress covers the wider picture.

What this means for you

Hair cortisol is a research measure in heart studies, not a test doctors use to assess heart risk; a 2024 expert review noted that it has so far been studied in research settings.¹⁰ As a measure of long-term cortisol, a hair test is consistent from one month to the next (r = 0.84 in one study), which is why researchers use it.¹⁹ It can show whether your cortisol has been running high over the past few months, which may be a useful prompt to look at stress, sleep and activity: meditation training, aerobic exercise and treating insomnia have each lowered hair cortisol in trials.²⁰¹⁷²¹ See how to lower cortisol.

A hair result does not tell you your risk of heart disease, and a normal result is not reassurance about your heart. For that, the standard checks are blood pressure, cholesterol and blood sugar, which a GP or pharmacist can arrange. If you have signs of Cushing's syndrome, such as easy bruising, a rounding red face and weak muscles in the upper arms and thighs, see a GP. If you think you or someone else is having a heart attack or stroke, call 999 (911 in the US) straight away.