Scientists in Australia have recently discovered the first clear molecular process that helps to explain how stress suppresses our immune defenses and makes us more vulnerable to getting sick. The author describes how the brain and the immune system talk with each other through a tiny protein called neuropeptide Y, which plays a surprising dual role in how our bodies deal with stress. Has a biological system that worked well for early humans faced with starvation turned against those of us living with the many new stresses of modern society?
Have you ever noticed that during periods of intense stress you are more prone to catch a cold or to come down with the flu? Scientists have long known that psychological stress, whether from a sudden trauma or a routine event of daily life such as a difficult commute, adversely affects our immune responses. How can we explain this? What are the cellular and molecular mechanisms that lead to a compromised immune system during stressful times?
We now know that many of the body’s important systems are closely interconnected. For instance, the immune system has connections to the nervous system and to the metabolic system. Many molecules that are used by the nervous system are also used by immune cells, and molecules in one system can have an important, and different, effect on the other. Now for the first time, interdisciplinary studies of a molecule found in both the nervous system and the immune system have revealed a clear link between stress and immune suppression.
Stress and Its Consequences
Psychological stress may be defined as any external condition or trauma that disturbs an individual’s psychological and physical well-being. This stress is subjective, as situations that stress one person may not stress another (for instance, I find air travel particularly unpleasant). People’s individual genetic makeup, combined with their life The irony is that for many people, adding stress-relieving activities to their busy schedule often creates additional stress. experiences, especially when they are young, results in a wide spectrum of responses to psychological stress. Stress is a worldwide challenge to health. Sometimes it comes from extreme conditions of poverty, starvation, persecution, or war. It can also be the result of caring for a sick family member, the loss of a loved one, troubled relationships, being in an occupation that involves a high level of responsibility or danger (police, airline pilots, air traffic controllers, firefighters), or the heavy workloads and the challenges of balancing professional and family life that are common in the Western world.
The most often noted manifestations of psychological stress are mental and physical fatigue, anxiety, anger, and depression. The second-most-common symptoms are immune disorders, especially an increased susceptibility to viral infections (herpes, flu, colds), bacterial or fungal infections (pneumonia, mycosis, meningitis), and inflammation (stomach ulcers, gastritis). Stress can also trigger allergies, asthma, autoimmune diseases such as juvenile diabetes, and inflammatory bowel disease. A link between chronic stress and the inability of immune cells to mobilize a strong defense against cancer has also been suggested.
Perhaps as a result of the considerable sources of psychological stress in our lives, the wellness industry has emerged, providing relaxation techniques, yoga, therapeutic massage, and psychological counseling. The irony is that for many people, adding stress-relieving activities to their busy schedule often creates additional stress. Moreover, our genes play an important role in how we react to stress, and so any positive response to relaxing activities varies considerably from person to person. The reality is that while relaxation cannot hurt, a sea change is not always possible, and a change of genetic makeup is impossible. Therefore, science must find new solutions to alleviate both the psychological and the immune-system side effects of stress. Here, then, is an opportunity for immunologists and brain researchers to collaborate.