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Highly hostile men are more likely to have higher levels of an immune system protein that's associated with several risk factors for cardiovascular problems, according to recent research published by psychologists Edward C. Suarez, PhD, James G. Lewis, PhD, and Cynthia Kuhn, PhD, in Brain, Behavior and Immunity (Vol. 16, No. 6).

The researchers' study of 62 healthy, nonsmoking men found that aggression and hostility can affect tumor necrosis factor (TNF)--a protein that is released by immune cells and other tissues. The protein, which marks inflammation of the arteries and tissues, helps direct immune system cells to the site of an infection or inflammation, among other things.

"Over the last 10 years, physicians and researchers have come to understand that heart disease is really an inflammatory disease involving injury to the arteries that is caused by a number of factors, such as smoking, high blood pressure, obesity and high cholesterol," Suarez says. And researchers have shown that such risk factors are associated with increases in TNF and other "inflammation markers." Moreover, atherosclerosis--an accumulation of unhealthy fatty deposits in the arteries--is characterized by high levels of TNF.

"What was not known until now was whether psychological factors often associated with great risk of heart disease, such as hostility and anger, are also associated with these same markers of inflammation," Suarez explains.

In their paper, Suarez and his colleagues examined the relationships of TNF to levels of aggression, hostility and anger. They found that healthy, nonsmoking men who scored high on hostility and physical aggression measures had higher TNF levels than those with moderate and low scores--even after controlling for age, race, alcohol use and educational status. Interestingly, says Suarez, those with moderate and low scores had similar TNF levels. Anger and verbal aggression scores were positively, but not significantly, associated with TNF levels.

"Overall, these results suggest that it is the attitude of ill-will toward others in addition to the tendency toward physical harm and verbal aggression that underlies the positive association between aggression and [TNF levels]," write the authors.

The paper is the first to document a relationship of aggression and hostility to one of the inflammatory markers that characterizes atherosclerosis, says Suarez, noting that the findings are independent of other traditional risk factors.