For many people, the stress that comes from standing up in front of a large group of people and giving a talk is akin to death. Indeed, some may say that fear of public speaking is even greater than their fear of their mortality.

While most of us are aware that stress is not a good thing, new research has found there is a biological basis for it. In fact, stress that stems from social situations, whether it be in anticipation of job interview or giving a speech, can affect the brain in ways that influence the immune system and thereby affect our health in a negative way.

The reason for this is because sensitivity to stress or social rejection can influence the body's inflammatory response. Although some people can eventually adapt to these stressors over time, chronic inflammation can have significant impact on our health, increasing the risk for a variety of chronic health conditions, including asthma, arthritis, heart disease, depression, and certain cancers.

In order to gain greater insight into this phenomenon, researchers enrolled 124 people (54 men and 70 women) into a study that examined how their bodies responded to social stress. Testing involved delivering a speech and performing difficult mathematical problems in awkward social situations. Mouth swabs were taken before and after the speeches were given in order to measure two key inflammatory markers, tumor necrosis factor (TNF-alpha) and interleukin 6 (IL-6).

In a follow-up session, volunteers received magnetic resonance imaging (MRI) brain scans to measure their neural activity while taking part in game that required social cooperation. Brain imaging was focused on the two regions that were known to respond to social stress, the dorsal anterior cingulate cortex (dACC) and the anterior insula.

Following a simulation of social rejection, researchers measured the differences in neural activity as they correlated with body's inflammatory response, as measured by the markers in question. What they found was that those individuals who experienced the greatest level of neural activity, which is presumably a measure of how they perceive and interpret social rejection, also had an greater increase in inflammatory activity.

The findings, published in the Proceedings of the National Academy of Science, support the important relationship between the mind and body. In other words, our mental and emotional state can have a profound influence on our physical well being, a fact that many of us are familiar with. While there is plenty of evidence, both scientific and anecdotal, that supports this understanding, there is not much data on how this relationship occurs. The current study is the first to actually identify certain biological pathways by which it can occur.