Such psychological factors have long been linked to heart disease, but the mechanism through which they harm the heart and blood vessels has not been established, Boyle and his colleagues note in the current issue of Brain, Behavior and Immunity. However, they add, there is mounting evidence that these emotions may contribute to inflammation in the body.

To investigate, Boyle and his team looked at levels of two inflammation markers, C3 and C4, in 313 men, who were an average of 50 years old, participating in the Air Force Health Study, a long-term investigation of the effects of Agent Orange. They assessed the men's level of hostility, anger and depression in 1985 and measured their C3 and C4 levels in 1992, 1997 and 2002.

Men with the highest levels of anger, depression and hostility also showed the greatest increase in C3 levels between 1992 and 2002, the researchers found. But there was no association between these psychological factors and levels of C4.

Research has linked higher levels of C3 to a greater risk of heart disease, abnormal heart rhythms and diabetes, Boyle and his team point out. They believe these findings provide additional support to the hypothesis that emotional factors contribute to health problems by influencing levels of chronic inflammation.

In an interview, Boyle pointed out that the assessment for hostility, anger and depression took place seven years before measurements of C3 and C4 began, and that all study participants were "very, very healthy," making it unlikely that, for example, the men might be depressed because of some underlying health problem that could also boost C3 levels. "That gives us a lot of confidence that these psychological factors precede the increase in inflammation."

While most people who are depressed will want to get treatment, Boyle noted, many individuals with hostile personalities may not be aware of it, and are thus unlikely to seek help.

However, there are definitely ways to lessen the impact of personality on health, he added. For example, he said, stress reduction techniques are helpful. "Even if you get angry, the consequences may be less severe if you're able to calm down quicker or if you're able to develop techniques to become angry less easily."

SOURCE: Brain, Behavior and Immunity, August 2007.

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