Stress linked to heart disease deaths

BMJ Group News

What do we know already?

Stress affects our bodies as well as how we feel. Stressful situations lead to changes in the brain and in the systems that control hormone levels. Cortisol is one of the hormones produced in response to stress.

A study earlier this year found that nurses who felt stressed at work were more likely to suffer from heart disease. There’s also research linking conditions like depression and panic attacks to heart problems, which could be due to the way these conditions affect stress hormones.

A new study measured the levels of cortisol in the urine of 861 people aged 65 and over. People were then followed for the next six years to see how stress hormone levels affected their health.

What does the new study say?

Higher cortisol levels were linked to a higher chance of dying of heart attacks and strokes during the six-year study. The researchers divided people into three groups based on their hormone levels. In group with the lowest levels, 3.5 percent of people died of heart problems or a stroke during the study. Among people with stress hormone levels in the top third, 6.6 percent died.

After taking into account other factors that could have made some people more vulnerable to heart disease or strokes, the researchers calculated that people with higher stress hormone levels had a risk of dying five times higher than those with levels in the bottom third.

The risk applied both to people who were healthy at the start of the study, and to people who already had heart and circulation problems.

How reliable is the research?

The researchers looked at stress hormone levels in people’s urine, but they didn’t ask people about whether they felt stressed or not. This makes it harder to draw conclusions about the role played by people's emotional state. We also don't know whether learning to cope with stress would make a difference.

The researchers say that being stressed a lot of the time, and being exposed to lots of stress hormones, could affect the body in a way that increases the risk of heart disease. For example, the effect of cortisol on fatty acids could encourage fat to accumulate round your organs, which increases the risk of heart disease.

But another possibility is that the body could lose its ability to regulate stress hormones for some other reason, which would still have harmful effects, but wouldn’t necessarily be caused by feeling stressed.

The researchers only measured cortisol levels once, at the start of the study. So, the research doesn’t take into account any changes in hormone levels over time.

Where does the study come from?

The study was done in Italy. It’s due to appear in the Journal of Clinical Endocrinology and Metabolism (published by the Endocrine Society) later this year.