Can Pain Affect the Immune System?
Ahh-Choo! Cold and flu season is here and you may be wondering if chronic pain affects your immune system. Without a fully operational defense system, the body is vulnerable to diseases and pathogens that attack every day. The immune system is a complex array of cells, chemical messengers, and tissues that orchestrate a defense system against infection and invaders. Sometimes this system works too well in the case of allergies and auto-immune diseases that are caused by an over-reactive immune system. Opposite of an over-reactive immune system is an under-reactive immune system; the most obvious example of which is AIDS caused by the HIV virus. But are there other things that can suppress the immune system? Can pain suppress the immune system? In order to answer that question, one needs to look at the interaction between pain, the nervous system, and the immune system.
Imagine pain as the "alarm system" for the body. When there is a threat of harm, the brain interprets that threat and signals the alarm. This alarm triggers a cascade of responses-a stress-response. In fact, many types of stressors can cause a stress-response like divorce, death, and financial hardship. One portion of the stress-response is the activation of the "fight or flight" nervous system, also called the sympathetic nervous system. In its most basic form, the sympathetic nervous system prepares the body to run, fight, and get away from a threat. The duration and magnitude of the stress has a great influence on whether or not the immune system will be affected by this cascade, either suppressed or enhanced. But once the alarm has been tripped, the link between the nervous system and immune system comes into play.
This link between the nervous system and the immune system is strong. Thinking in terms of the "fight or flight" system, the body generally has one basic over-riding instinct: to survive. When chased by a lion or burned by a stove, the reactions and responses are short-term and quick. In order to divert energy to muscles for running or moving, the body can shut down more long-term, high-energy processes like digestion, sexual and immunity functions. Actually, this relationship is more complex than a simple shut down procedure because during the initial stress-response the nervous system fine tunes and enhances parts of immunity. But as the stressor continues, the nervous system triggers the shutdown of immunity and actually starts to disassemble it.
Stress-induced immunosuppression has been documented for over sixty years. The hormones produced by the sympathetic nervous system have been shown to suppress and kill the cells critical for immunity. Thus, anything that triggers the sympathetic nervous system has the potential to suppress immunity. Which leads this discussion to the original question: Can pain suppress the immune system? Essentially the answer is yes with some caveats because the interaction between the stress-response and immunity depends on duration of a stressor like pain, magnitude of the stress and probably many other individual factors that are being discovered by psychoneuroimmunologists. In some cases, pain may actually enhance immunity or feed into an over-active immune system. The interaction between pain, the nervous system and immune system is very complex indeed.
During this flu and cold season, be aware that this complex interaction may be affecting your immunity. Take all the necessary precautions to avoid getting sick like washing your hands, avoiding sick people, and maintaining your health. Diseases and pathogens attack the body every day, helping the immune system can make all the difference in the world.
Reference: Why Zebras Don't Get Ulcers by Robert M. Sapolsky