How Stress Increases Cardiovascular Risk

Researchers have found that mental stress contributes to the risk of cardiac disease by causing changes in the endothelial cells of blood vessels that interfere with their ability to dilate. This serves to restrict the flow of blood, a condition that can increase the risk of a heart attack or stroke.

It is well known that grief, anger, shock or other severely stressful events can cause sudden cardiac death. How this happens at the molecular level was not clear. Now a study published in the May 20, 2002, issue of Circulation describes the biochemical effect of mental stress on blood vessels.

The researchers, from University Hospital (Zurich, Switzerland), studied subjects aged 20-31 years old with no known cardiovascular risk factors. Ultrasound was used in five individuals to assess the ability of their blood vessels to dilate both before and 10 minutes after a three-minute mental stress task. Six subjects had dilation measured before and after the task while being infused with a drug called an ETa (endothelin-A) receptor blocker that causes dilation. For comparison, saline was infused in a control group of three people. For the mental stress task, subjects had to respond as quickly as possible to colored lights by pushing a button of the corresponding color. Researchers found a significant decrease in blood-vessel dilation after mental stress. The mental stress test increased average arterial blood pressure from 83-96 millimeters of mercury (mm Hg) and heart rate from 63-81 beats per minute. Flow-mediated dilation was reduced by half, from 8.0 to 4.1.

Administration of the ETa receptor blocker prevented this significant drop in dilation capability (8.6 before vs. 9.4 at 10 minutes after). The investigators believe this response identifies ETa activation as a mechanism responsible for endothelial dysfunction; therefore, blocking ETa receptors may be a novel way to prevent atherosclerosis.

"Endothelial dysfunction induced by mental stress offers a novel and unique link between psychological factors and the cause of atherosclerosis, similar to other risk factors that impair function such as high cholesterol or high blood pressure,” explained Dr. Georg Noll.



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University Hospital (Zurich)