Though it's commonly expressed in the medical field that chronic stress and anxiety can cause heart attacks, a recent study, published June 22nd in Nature Medicine, identifies the mechanism that links the two. Scientists at the Harvard Medical School of Boston, lead by Ph.D. Matthais Nahrendorf, have worked to examine the cause of this correlation, with some pretty conclusive results.

The Study

Nahrendorf and his team began by conducting blood tests on 29 doctors working in the intensive care unit of Massachusetts General Hospital. These doctors emphasized that their stress and anxiety levels rose on the job, attributing their heightened anxiety to the frequency of life-or-death situations and the necessity of quick decision making during their shifts.

Blood tests were paired with surveys asking the doctors to identify their anxiety levels, and this information was collected both during these doctors shifts and during their non-work hours. It was identified that in all the participating doctors, levels of white blood cells rose during participation in stressful ICU shifts, with white blood cell overproduction correlating directly with reported increases in anxiety.

Researchers confirmed their findings by overseeing similar studies on mice. Mice were placed in a variety of situations determined to be stressful, and their white blood cell levels were compared to anxiety-free 'control mice'. The stressed mice were subjected to sudden changes between light and darkness, tilted cages, and rotations between crowded quarters and isolation. Results similar to those found in doctors were discovered: 'stressed' mice showed distinctly heightened white blood cell counts when compared to non-stressed mice.

What White Bloods Cells Have to Do with Anxiety

The combination of these two studies identifies the culprit in anxiety-related heart attacks and strokes: white blood cells. The body's fight or flight response to high anxiety levels facilitates the release of these white blood cells, which are designed to increase resistance to disease and infection. However, an overabundance of white blood cells in arteries, combined with plaque which accumulated on artery walls, can cause clots and blockage and consequently lead to heart attacks.

Nahrendorf's research team was able to identify the hormone and receptor responsible for the release of these white blood cells, and was even able to block the receptor in order to decrease levels of white blood cells in stressed mice. California biologist, Lynn Hedrick, told Science Magazine that “if we can develop a drug that targets the receptor, this may be very clinically relevant," suggesting that the results of this study will go far in helping to prevent anxiety-related heart attacks.

Date of original publication:

Sources

Timo Heidt, Hendrik B Sages, Garbriel Courties, Partha Dutta, Yoshiko Iwamoto, Alex Zaltsman, Constantin von zur Muhlem, Christop Bode, Gregory L Fricchione, John Denninger, Charles P Lin, Claudio Vinegoni, Peter Libby Filip K Swirski, Ralph Weissleder & Matthias Nahrendorf. Chronic variable stress activates hematopoietic stem cells. Nature Medicine, 2014; DOI:10.1038/nm.3589

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