The part of the brain linking stress to the risk of heart attack and stroke has been identified for the first time, researchers say.
The findings could indicate that reducing stress has an important physical as well as psychological benefit, scientists said on Thursday.
The study showed that people with heightened activity in the amygdala, an area of the brain linked to stress, may be at greater risk of heart disease and stroke.
![Reducing stress could have an important physical as well as psychological benefit, researches say.](/web/20170414015723im_/http://www.theage.com.au/content/dam/images/1/2/1/y/3/r/image.related.articleLeadwide.620x349.gtpxrk.png/1484194108359.jpg)
Publishing their work in The Lancet medical journal, the researchers said the stress signalled in the amygdala was also linked to increased bone marrow activity and to inflammation in the arteries, which can cause heart attack and stroke.
Exploring the links, the scientists said a plausible biological mechanism could be that the amygdala triggers the bone marrow to produce extra white blood cells, which then cause the arteries to develop plaques and become inflamed.
![The amygdala is a small structure in the brain that is responsible for emotions and survival instincts.](/web/20170414015723im_/http://www.theage.com.au/content/dam/images/g/j/n/n/o/v/image.related.articleLeadNarrow.300x0.gtpxrk.png/1484194108359.jpg)
"Our results provide a unique insight into how stress may lead to cardiovascular disease," said Ahmed Tawakol of Massachusetts General Hospital and Harvard Medical School in the United States, who led the study.
"This raises the possibility that reducing stress could produce benefits that extend beyond an improved sense of psychological wellbeing."
Smoking, high blood pressure and diabetes are well-established risk factors for heart disease, and anecdotal evidence has pointed to chronic stress as another possible risk.
Studies in animals have previously found a link between stress and higher activity in bone marrow and arteries, but until now scientists were unsure if this was the case in people.
Other research has found the amygdala is more active in people with post-traumatic stress disorder, anxiety and depression. But before this study, none had found the region of the brain that links stress to heart attack and stroke risk.
In this research, scientists gave 293 patients brain and body scans to record their brain, bone marrow and spleen activity and inflammation of their arteries.
The patients were then tracked for an average of 3.7 years to see if they developed heart disease. In this time 22 patients had cardiovascular events - including heart attack, angina, heart failure, stroke and peripheral arterial disease.
The researchers found that those with higher amygdala activity were more likely to have subsequent cardiovascular disease, and more likely to develop problems sooner than those with lower activity.
Emily Reeve, a cardiac nurse at the British Heart Foundation charity, said the study's findings should lead to better understanding of how to prevent heart disease.
"The link between stress and increased risk of developing heart disease has previously focused on the lifestyle habits people take up when they feel stressed such as smoking, drinking ... and overeating," she said.
"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."
Commenting on the study, Ilze Bot of Leiden University in the Netherlands, said more research was needed to confirm the mechanism identified by the scientists, but added that it could be useful given increasing levels of stress in society.
"In the past decade, more and more individuals experience psychosocial stress on a daily basis," Dr Bot 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.
"These clinical data establish a connection between stress and cardiovascular disease, thus identifying chronic stress as a true risk factor for acute cardiovascular syndromes, which could, given the increasing number of individuals with chronic stress, be included in risk assessments of cardiovascular disease in daily clinical practice."
Reuters, PA