Stress and Health

It is by now very well established that chronic stress makes us sick. But how? What is the relationship between states of mind and the immune system?

Nature has a little piece this week on Steve Cole, an immunologist who studies these connections. His work seems to show measurable differences in gene expression -- that is, which genes are active -- between unhappy and happy people, between lonely and sociable people, and between those who are stressed and those who are not. Which is interesting but not, as far as I can see, an explanation. But this might be:

people who were isolated and under stress faced greater risk of injuries that could cause bacterial infection — and thus would need to respond by ramping up genes associated with inflammation, to help heal wounds and fight off those infections. But modern stresses lead to chronic and unhelpful inflammation, which over time damages the body's tissues, increasing the risk of chronic diseases such as atherosclerosis, cancer and diabetes.

So when you are really stressed, ancient systems in your body assume this means you are at great risk of physical injury and prepare themselves for battle. But those defense systems do long-term damage to our bodies. The sort of modern stress that comes from loneliness, helplessness, and ennui can drag on for years, and over time the price of maintaining our stress response kills us.