How stress influences disease and health

A study carried out by the Carnegie Mellon University, US, has shown for the first time that the effect of psychological stress on the body is to disrupt its ability to regulate inflammation, which in turn leads to the creation and progression of disease.

Stress prevents the inflammation-regulating hormone cortisol from functioning by partly decreasing tissue sensitivity to the hormone, meaning immune cells become insensitive to cortisol’s effects.

Lead author Sheldon Cohen, the Robert E. Doherty Professor of Psychology within CMU’s Dietrich College of Humanities and Social Sciences, has published work showing that those suffering from psychological stress are more susceptible to the common cold, and used the cold as the model for testing the theory of how  stress influences disease.

Symptoms of the common cold are a side-effect of the body’s immune system fighting the virus – the greater the body’s inflammatory response in fighting infection, the more symptoms experienced. In Cohen’s first study 276 adults were interviewed intensively for stress, and then exposed to the common cold virus. Here he found that a prolonged stressful event was associated with the body’s inability to respond to hormonal signals that should regulate inflammation, leading to the increased likelihood of developing a cold.

In the second study, 79 people were assessed for their ability to regulate the inflammatory response and then exposed to the cold virus, during which time they were monitored for the production of pro-inflammatory cytokines, which are the chemical messengers that trigger inflammation. The results showed that those less able to regulate the inflammatory response produced more cytokines on infection.

From these studies, Cohen determines that during times of stress, the immune system is unable to respond to hormonal control and end up producing levels of inflammation that promote disease. Inflammation plays a role in diseases such as asthma and cardiovascular disorders. This study can help determine which diseases may be influenced by stress, and for helping to prevent disease in chronically stressed people.

Source: Proceedings of the National Academy of Sciences of the USA

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First Published April 2012

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