C-reactive protein, or CRP, is made by the liver in response to inflammation. High levels of CRP can indicate risk of cardiovascular disease, although it's not at all clear how CRP and disease are connected. (The plaque that clogs arteries probably has something to do with it.) Being angry or depressed also increases the risk of cardiovascular disease and having higher levels of some chemicals linked to inflammation. A researcher at Duke looked at whether angry, depressed people have high levels of CRP.

What the researcher wanted to know: Are anger, hostility, and depressive symptoms related to levels of C-reactive protein in healthy people?

What he did: The researcher used newspapers and fliers to recruit 127 people who were healthy, didn't smoke, and had normal blood pressure. People were ruled out for having any condition ranging from allergies to cancer—anything that could influence levels of C-reactive protein in their blood. A blood sample was taken from each person. And each participant filled out questionnaires to assess anger, hostility, and depressive symptoms.

What he found: People with more anger and worse depressive symptoms had higher levels of C-reactive protein. (This was still true when he adjusted for gender, age, body mass index, alcohol use, exercise, and blood lipid levels.)

What the study means to you: Being angry and depressed seems to affect you physically. No one really understands the relationship between C-reactive protein and cardiovascular disease, but it seems clear that there is some link.

Caveats: You can't tell for sure from this study that anger and depression cause elevated CRP levels; they could all be caused by something else. It seems more likely that anger and depression are the cause, though.

Find out more: Anger management, from the American Psychological Association

About depression from the National Institute of Mental Health

Read the article: Suarez, E.C. "C-Reactive Protein Is Associated With Psychological Risk Factors of Cardiovascular Diseases in Apparently Healthy Adults." Psychosomatic Medicine. September/October 2004, Vol. 66, No. 5, pp. 684–691.

Abstract online: www.psychosomaticmedicine.org