Scientists have identified what may be an important biological link between stress and the common cold. The culprit: interleukin-6 (IL-6), a chemical pathway used by the immune system.

In a 1991 report in the New England Journal of Medicine, Sheldon Cohen, PhD, of Carnegie Mellon University in Pittsburgh had earlier found a clear link between psychological stress and a propensity to be infected by respiratory viruses. The new work by Cohen and colleagues (William Doyle, PhD, and David Skoner, MD, of The Children's' Hospital of Pittsburgh) finds that the cytokine IL-6 may be a major pathway between mind and body by which stress makes the body more susceptible to developing infection and symptoms of respiratory illness.

"Even with certain reservations, this is the first study to provide evidence consistent with the hypothetical model that psychological stress influences upper respiratory infectious illness through a biological pathway," they report in the March issue of Psychosomatic Medicine.

The finding is a significant step forward in establishing a direct biological link between stress and human illness. Until now, Cohen and his colleagues have been able to establish stress as a risk factor for respiratory illness, but they have only been able to speculate on the potential biological pathway that links stress to greater risks of colds and flu.

For this study, Cohen and his colleagues measured the levels of psychological stress of 55 adult volunteers before infecting them with an influenza A virus and quarantining them for eight days.

All participants developed verified infection with the same strain of influenza A virus. At the end of each day, the participants rated the severity of their respiratory symptoms -- sneezing, nasal congestion and discharge, sore throat, cough, malaise, headache, and chilliness. Their mucus production was measured by collecting and weighing used tissues.

Levels of the IL-6 were measured daily in nasa
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Contact: Teresa Thomas
ts2h@andrew.cmu.edu
412-268-3580
Center for the Advancement of Health
22-Mar-1999