People with heightened activity in the amygdala – a region of the brain involved in stress – may have a greater risk of heart disease and stroke, according to a study published in The Lancet journal on Thursday that may lead to new treatments for stress-related cardiovascular problems.
The study provides new insights into the possible mechanism by which stress can lead to cardiovascular disease in humans, researchers said.
The researchers suggest that these findings could eventually lead to new ways to target and treat stress-related cardiovascular risk.
Smoking, high blood pressure and diabetes are well-known risk factors for cardiovascular disease and chronic psychosocial stress could also be a risk factor.
Previously, animal studies identified a link between stress and higher activity in the bone marrow and arteries, but it has remained unclear whether this applies to humans.
No previous study has identified the region of the brain that links stress to the risk of heart attack and stroke.
In this study, 293 patients were given a combined PET/CT scan to record their brain, bone marrow and spleen activity and inflammation of their arteries.
Patients were then tracked for an average of 3.7 years to see if they developed cardiovascular disease. In this time 22 patients had cardiovascular events including heart attack, angina, heart failure, stroke and peripheral arterial disease.
Those with higher amygdala activity had a greater risk of subsequent cardiovascular disease and developed problems sooner than those with lower activity, researchers said.
They also found that the heightened activity in the amygdala was linked to increased bone marrow activity and inflammation in the arteries, and suggest that this may cause the increased cardiovascular risk.
The researchers suggest a possible biological mechanism, whereby the amygdala signals to the bone marrow to produce extra white blood cells, which in turn act on the arteries causing them to develop plaques and become inflamed, which can cause heart attack and stroke.
In a small sub-study, 13 patients who had a history of PTSD also had their stress levels assessed by a psychologist, underwent a PET scan and had their levels of C-reactive protein – a protein that indicates levels of inflammation in the body – measured.
Those who reported the highest levels of stress had the highest levels of amygdala activity along with more signs of inflammation in their blood and the walls of their arteries.
"Our results provide a unique insight into how stress may lead to cardiovascular disease. This raises the possibility that reducing stress could produce benefits that extend beyond an improved sense of psychological wellbeing," said lead author Ahmed Tawakol from Massachusetts General Hospital and Harvard Medical School in the US.
"Eventually, chronic stress could be treated as an important risk factor for cardiovascular disease, which is routinely screened for and effectively managed like other major cardiovascular disease risk factors," said Tawakol.