Doctors discover why stressed out people have more heart attacks

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Doctors have long believed that chronic stress causes strokes and heart attacks, but they've not been able to work out why, until now.

Those patients who developed cardiovascular disease were more likely to exhibit higher activity in the amygdala - an almond-shaped area of the brain linked to fear responses and pleasure. Now, a study in the journal The Lancet this week finds an interesting link between stress and the heart: The brain.

The team think this is because the stressed brain sends signals to the bone marrow to produce extra white blood cells, which play a crucial role in supporting the immune system - a natural defence mechanism if someone feels under threat.

"Our results provide a unique insight into how stress may lead to cardiovascular disease", lead author Dr Ahmed Tawakol, of Harvard Medical School and Massachusetts General Hospital, said.

In the study, the researchers looked at two groups of patients, the first of which included almost 300 adults ages 30 and up. In this time, 22 patients had cardiovascular ailments including heart attack, angina, heart failure, stroke and peripheral arterial disease.

The second very small study, of 13 patients, looked at the relationship between stress levels and inflammation in the body.

"Exploring the brain's management of stress and discovering why it increases the risk of heart disease will allow us to develop new ways of managing chronic psychological stress".

The link between the amygdala and cardiovascular disease events remained significant even after the researchers took other cardiovascular risk factors into account, such as smoking, diabetes or hypertension. But if it were, then people with the most active amygdalas would be the ones with the highest risk of heart attack and strokes. It was found that heightened activity in the amygdala is associated with a greater risk of heart disease and stroke. Image analyses and cardiovascular disease event adjudication were done by mutually blinded researchers.

And the higher the levels of activity were in the amygdala at the study's start, the sooner these events occurred, the researchers found. However, researchers also noted that more research is needed in order to definitively conclude that stress could actively cause serious heart events. The findings also underscore the importance of addressing stress in order to reduce health risks. "We don't yet have large, randomized studies showing that reducing stress leads to lower cardiovascular disease risk, but studies like this one showing a potential mechanism and those showing a benefit to altering this mechanism make a strong case for screening patients for stress", he said. "Heavy workloads, job insecurity, or living in poverty are circumstances that can result in chronically increased stress, which in turn can lead to chronic psychological disorders such as depression", wrote Dr Ilze Bot, from the Leiden Academic Centre for Drug Research, Leiden University, The Netherlands in a comment published with the study.