Research led by Peggy Zoccola, Ph.D., an assistant professor of psychology at Ohio University, has found that dwelling upon events that are stressful can significantly increase inflammatory chemicals in the body. The researchers tested 34 healthy young women giving public presentations for job interviews. Afterward, half were asked to contemplate their performances while the others were asked to think about neutral events and images.

While all of the women initially experienced significantly higher levels of C-reactive protein (CRP), the levels continued to rise for at least one hour afterward for the performance-ruminating group, but returned to normal during the same time period for those that pondered neutral thoughts.

CRP is produced in the liver and is known to rise following an injury or in a chronic inflammatory condition. “The immune system plays an important role in various cardiovascular disorders such as heart disease, as well as cancer, dementia and autoimmune diseases,” states Zoccola.