How stress can inflame many diseases
Cortisol, or the 'stress hormone', is produced naturally by the body to assist in various processes, including regulating blood pressure and cardiovascular functions, and boosting metabolism. The steroid hormone, which is produced by the adrenal glands, also enhances the integrity of blood vessels and reduces allergic and inflammatory responses. But stress can thwart the efforts of cortisol, say researchers at Carnegie Mellon University in Pittsburgh, in the US. The study is published in the Proceedings of the National Academy of Sciences.
Lead researcher Sheldon Cohen, a psychology professor whose work focuses on the effects of stress on the mind and body, has found that prolonged stress causes immune cells to become insensitive to cortisol's regulatory effect on inflammatory response. In turn, runaway inflammation is thought to promote the development and progression of many diseases.
Psychological stress is linked with a greater risk of depression, heart disease and infectious diseases. But until this new research, it was not clear exactly how stress influences disease and health.
The team did two studies. In the first one, after completing an intensive stress interview, 276 healthy adults were exposed to a virus that causes the common cold and were monitored in quarantine for five days for signs of infection. Prolonged stress was found to be linked with the inability to regulate inflammatory response. These people were more likely to develop colds when exposed to the virus.
In the second study, 79 healthy participants were assessed for their ability to regulate the inflammatory response. They were then exposed to a cold virus and monitored for the production of pro-inflammatory cytokines, the chemical messengers that trigger inflammation.
Those who were less able to regulate the inflammatory response produced more of these messengers when infected. 'The immune system's ability to regulate inflammation predicts who will develop a cold, and provides an explanation of how stress can promote disease,' Cohen says.
'When under stress, cells of the immune system are unable to respond to hormonal control and produce levels of inflammation that promote disease. Because inflammation plays a role in many diseases, this model suggests why stress has an impact as well.'