SCIENTISTS believe they have discovered why psychological stress can lead to physical pain.
A research team at Carnegie Mellon University in Pitts- burgh found that chronic psychological stress is associated with the body losing its ability to regulate the inflammatory response.
Published in the Proceedings of the National Academy of Sciences, the research shows the effects of psychological stress on the body's ability to regulate inflammation can lead to the development and progression of disease.
Sheldon Cohen, professor of psychology at the university's Dietrich College of Humanities and Social Sciences, said prolonged stress alters the effectiveness of cortisol to regulate the inflammatory response because it decreases tissue sensitivity to the hormone.
Specifically, immune cells become insensitive to cortisol's regulatory effect and in turn inflammation is thought to promote the development and progression of many diseases.
Prof Cohen: "Inflammation is partly regulated by the hormone cortisol and when cortisol is not allowed to serve this function, inflammation can get out of control."
The professor, whose early work showed that people suffering from psychological stress are more susceptible to developing colds, used the common cold as the model for testing his theory. With the common cold, symptoms are not caused by the virus. They are instead a side- effect of the inflammatory response that is triggered as part of the body's effort to fight infection.
The greater the body's inflammatory response to the virus, the greater is the likelihood of experiencing cold symptoms.
Prof Cohen said: "The immune system's ability to regulate inflammation provides an explanation of how stress can promote disease."
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