MASSACHUSETTS – While the link between stress and heart attacks and strokes is well known, scientists have long failed to establish the exact cause.
Now they believe they have finally cracked it, and it all comes down to heightened activity in the amygdala, the part of the brain that reacts to stress.
The amygdala readies the body for harmful experiences, such as being physically attacked, by telling the bone marrow to temporarily produce more white blood cells. These help fight infection and repair damage to the body.
Chronic stress can lead to a similar reaction, but in the absence of physical damage to repair, excess white blood cells remain in the system. Experts now believe that this in turn can form plaque in the arteries and lead to heart disease, the Telegraph reports.
For the study, researchers at Harvard Medical School scanned 293 patients to monitor activity of their brain, bone marrow, spleen and inflammation of their arteries.
The patients were tracked for an average of 3.7 years and during this period 22 experienced cardiovascular events such as heart attack, angina, heart failure, stroke and peripheral arterial disease.
The findings showed that those with higher activity in the amygdala had a greater risk of cardiovascular disease. They also developed problems sooner compared with those with lower activity.
Heightened amygdala activity was linked to increased bone marrow activity and inflammation in the arteries suggesting that this was causing the increased risk of heart disease.
Lead author Dr Ahmed Tawakol, of Harvard Medical School and Massachusetts General Hospital, said that the results provided 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 well-being," he indicated.
Researchers, whose findings were published in The Lancet medical journal, say that chronic social stress should also now be considered a major danger alongside smoking, high blood pressure and diabetes when it comes to assessing heart disease risk.