A new study from NIH adds good evidence to an idea that may seem intuitive to many: the angrier you are, the greater your risk for heart attack and stroke.

The research team at NIH followed over 5,600 Italians for three years. At the beginning of the study, the participants were rated on six personality traits (trust, straightforwardness, altruism, compliance, modesty and tender mindedness), and from this it was determined how "antagonistic" or "agreeable" they were.

People who were more antagonistic at the beginning of the study had thicker artery walls. This was also true three years later.

To determine the participants’ heart and stroke risk, Sutin measured the thickness of the carotid arteries of the neck, which is considered a reliable marker: the thicker the artery walls, the greater the risk.

People who were more antagonistic at the beginning of the study had thicker artery walls. This was also true three years later. In fact, people in the bottom 10% of agreeableness had a 40% greater chance at having thicker artery walls, which suggests that they may be putting their heart health in jeopardy.

The effect was actually more pronounced for women, even though men tended to have thicker artery walls overall. "Women who scored high on antagonism-related traits tended to close the gap, developing arterial thickness similar to antagonistic men. Whereas women with agreeable traits had much thinner arterial walls than men with agreeable traits, antagonism had a much stronger association with arterial thickness in women", says Sutin.

Even angry young people showed the trend towards thicker walls, indicating that this relationship may start at an earlier age than one might think (since thickened arteries typically develop with age). It’s likely that the finding will apply to other populations of people, but more research will be needed to explore this interesting relationship. In the meantime, it’s probably a good idea to find some healthy ways to release your anger and put a little less pressure on the heart.

The study was published in the August 16, 2010 online issue of Hypertension: Journal of the American Heart Association.