Stress is no stranger to Carnegie Mellon students, and unfortunately in today’s society, stress is prevalent in many people’s lives. Faced with this issue, a team of researchers at Carnegie Mellon recently found a direct correlation between increased psychological stresses and a decrease in the body’s ability to cope with disease.

The team, led by psychology professor Sheldon Cohen, observed that an increase in stress levels led to increased levels of a hormone called cortisol, which has been studied and identified as a stress-related hormone.

Scientists understand that cortisol plays an important role in various daily functions as it circulates in the bloodstream, so increased levels of the hormone could have adverse effects on the body.

The study, recently published in the Proceedings of the National Academy of the Sciences, focused on how increased levels of cortisol contributed to the body’s reduced ability to fight off disease.

Cohen’s group found that stress increased the symptoms of inflammatory diseases such as the common cold, cardiovascular disease, and asthma. Symptoms caused by these diseases like sneezing, coughing, and runny nose happen when the immune system responds in excess to the disease pathogens. Cohen said that his team “aimed to understand why stressed people were more likely to experience the symptoms caused by these diseases.”

The human body’s immune system is a massive network that produces and disperses chemicals needed to fight disease. With inflammatory diseases, the immune system releases pro-inflammatory proteins called cytokines that go to the area of the infection and orchestrate the immune response. The key to fighting diseases is to have just the right amount of these pro-inflammatory proteins. When there are too many, that’s when symptoms appear.

Cortisol plays a large role in regulating the amount of cytokines present to fight the infection. Cohen’s team found that under stress, the immune cells cannot interact with cortisol, preventing the regulation of cytokines. Therefore, highly stressed people will have unregulated production of cytokines, leading to a weaker immune system.

Cohen’s team included researchers from the University of Pittsburgh, who carried out interviews with adult participants of the study to understand what levels of stress they were experiencing. Cohen explained that their stress analysis interviews were intensive and questioned participants about “major events over the last year of their lives and considered how threatening these events would be to an average person.” These interviews were key in drawing the link between stress and immune response.

“We had been trying to do this [research] for a long time,” Cohen said, “but this time we really nailed the pathway.” Cohen and his team found the study extremely rewarding because they believe their results “can be applied to a broad range of diseases.”