Scientists discover how stress causes heart attacks and strokes

Surplus white blood cells are linked to plaques in the arteries


A new study by researchers at Harvard Medical School has shed light on why stresses associated with modern life could be a contributing factor to heart attacks, angina and strokes.

Stress has long been associated with a range of health problems, but the study is the first to demonstrate a link between stress responses in the brain and an increased risk of cardiovascular disease in humans.

US scientists studied the brain, bone marrow, spleen and arteries of nearly 300 volunteers and monitored them for four years to see whether they developed signs of heart disease.

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The results, published in The Lancet, indicate that "people who have heightened activity in a part of the brain linked to stress – the amygdala – are more likely to develop cardiovascular disease", says the Daily Telegraph.

Over the four-year study, 22 patients had cardiovascular 'events' including heart attack, angina, heart failure, stroke and peripheral arterial disease, The Lancet reports, with a disproportionate number of these patients exhibiting higher than average activity in the amygdala.

The amygdala controls the volume of white blood cells produced by the body's bone marrow, speeding up production when more are needed to fight off infections or speed up recovery from an injury.

High levels of stress trigger the amygdala to raise white blood cell production in anticipation of imminent danger or harm.

Chronic ongoing stress, such as that linked to a busy, high-pressure lifestyle, could therefore lead to a build-up of surplus white blood cells, which in turn can combine with cholesterol, calcium and fat to form the plaques in the arteries associated with heart disease.

Lead author Dr Ahmed Tawako told the BBC that more research was needed to confirm the connection, but that the study "raises the possibility" that reducing stress could produce physical benefits "beyond an improved sense of psychological wellbeing".

He added: "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."

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