Many factors contribute to a person's risk of developing cardiovascular disease, known commonly as heart disease. Researchers have found that stress, diet, smoking and weight, among other things, contribute to the chance that someone will have a heart attack or stroke. Now, as Rose Hoban reports, researchers are looking more closely at personality and how that might help predict future heart disease.

Psychologist Jesse Stewart from the Indiana University Center for Aging Research says prior studies have looked at the relationship of both depression and hostility to cardiovascular problems. He says the presence of each of these personality attributes has been shown to predispose people to heart disease. So, Stewart set out to study the two traits together.

"The main reason why these psychological factors need to be examined together is they are correlated, which means they tend to co-occur within individuals," Stewart explains. "So, someone experiencing depressive symptoms is more likely to be hostile than someone who is not."

Stewart worked with more than 300 older adults who were already part of another study looking at cardiovascular disease and gave them questionnaires to determine if they had a hostile personality or were depressed or both. The questionnaires asked subjects to agree or disagree with statements such as, "I think most people lie to get ahead."

The subjects also had their blood drawn.

Then the blood was analyzed to measure the levels of some inflammatory proteins which provide information about the status of their immune system and how active it is.

"We were specifically targeting two inflammatory proteins ? that had been shown to be predictive of future heart disease, so, if you have high levels today, you're at greater risk for a cardiac event in the future," Stewart says.

Stewart and his colleagues followed the subjects for six years. He says they found that those who reported feeling both depressed and hostile had especially high levels of the inflammatory proteins in their blood.

Stewart says this adds fuel to the belief that complex interactions between psychological factors and the body can predispose people to heart disease, and that perhaps heart disease risk could be reduced by treating those factors.

He says there could be many applications to this knowledge. For example, individuals experiencing both depression and hostility might be considered a high risk population for which early intervention and treatment would be warranted.

"There are efforts now to develop treatments ? psychological treatments ? to reduce depression and hostility, with the hope of preventing or delaying the onset of heart disease," Stewart says.

Stewart says psychological risk factors for heart disease need to be studied more thoroughly. He says they easily could contribute as much to heart disease risk as smoking or high blood pressure.

Stewart's research is published in the journal Psychosomatic Medicine.