According to a study done by researchers at Indiana University-Purdue University Indianapolis the risk of heart disease increases with hostility and depression.
The study, led by Jesse Stewart, Ph.D., assistant professor of psychology, found that hostility and depression appear to act together in a complex way to elevate inflammatory proteins in the human body, possibly putting the dangerous duo on the list of risk factors for heart disease along with high blood pressure, elevated cholesterol, and smoking.
The researchers found that hostility enhances inflammatory processes relevant to heart disease only in the presence of depressive symptoms.
For the study, the researchers examined associations of depressive symptoms and hostility with blood levels of two inflammatory proteins, interleukin-6 and C-reactive protein, that are predictive of future heart disease.
Participants in the study were 316 healthy men and women aged 50-70.
"In our study, we looked at depression and hostility simultaneously, and we found that the relationship of these negative emotions to inflammatory markers is more complex and much stronger than depression or hostility individually," said Dr. Stewart.
Dr. Stewart said that the strength of the association of psychological factors with future heart disease is similar to that of traditional risk factors like smoking, high blood pressure, and elevated cholesterol.
"There are of course mental health reasons to treat depression and hostility. Now we know there is a physical health reason - the link to cardiovascular diseases," Dr. Stewart said.
The study is published in the February-March 2008 issue of Psychosomatic Medicine.