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Scientists look at why stress can lead to heart attacks

Researchers are looking closely at what they believe links chronic stress and heart attacks: an overproduction of white blood cells.

The body makes an excess of white blood cells during times of stress. The white blood cells, or leukocytes, are important for fighting infection, "but if you have too many of them, or they are in the wrong place, they can be harmful," Matthias Nahrendorf of Harvard Medical School, a co-author of the study, told Agence France-Presse. The cells can stick to artery walls, restricting blood flow and helping form blood clots.

Nahrendorf and a group of researchers studied 29 medical residents working in a high-stress ICU, and had them fill out questionnaires on stress levels. They also collected blood samples during working hours and off-hours. The scientists saw an overproduction of white blood cells during stressful periods. A subsequent experiment on mice showed a similar increase in white blood cell counts after having stress induced, and the arterial buildup apparently resulting from the cells.

While the researchers will continue to explore this potential link between stress and heart attacks, Nahrendorf stresses that smoking, high cholesterol, genetics, and high blood pressure are also risk factors in having a heart attack or stroke.