Peggy Zoccola, an assistant professor of psychology at Ohio University in Athens, and colleagues discovered when study participants were asked to ruminate on a stressful incident, their levels of C-reactive protein, a marker of tissue inflammation, rose.
"Much of the past work has looked at this in non-experimental designs. Researchers have asked people to report their tendency to ruminate, and then looked to see if it connected to physiological issues," Zoccola said in a statement. "It's been correlational for the most part."
The research team asked 34 healthy young women to give a speech about her candidacy for a job to two interviewers in white laboratory coats, who listened with stone-faced expressions, Zoccola said.
Half of the study participants were asked to contemplate their performance in the public speaking task, while the other half was asked to think about neutral images and activities, such as sailing ships or grocery store trips.
Then the researchers drew blood samples. The samples showed the levels of C-reactive protein were significantly higher in the subjects who were asked to dwell on the speech, Zoccola said.
Zoccola presented the findings at the annual meeting of the American Psychosomatic Society in Miami.