Google “books on positive thinking” and you will find a whole host of literature about the power of positive thinking. One might then naturally conclude that negative thoughts have just as much power in them as positive. And you would be correct. If our thoughts can affect our behaviors, can what we think and feel really affect our bodies. Can we think our way into being ill? Or, for that matter, into being well? Decades of research have shown that our behavior and thoughts can influence the immune system. According to Professor Steven Maier from the University of Colorado, stress can trigger an immune response, not unlike that of an infection.
When We Are Sick
Maier explains, when we are sick our brain signals the body to trigger a “sick response’ by sending out immune cells [macrophages] that release chemicals [cytokines] which cause a variety of both physical and behavioral changes to occur such as fever, chills, reduced eating or drinking, and increased anxiety levels. Stress hormones like Cortisol are also released.
To prove this Maier conducted two experiments. First, he blocked the brain from receiving cytokines in sick animals which then began to behave normally. Second, he introduced cytokines to the brain of healthy animals which then began to show signs of illness.
But how does the brain know there is an illness? In the brain, there is a membrane called the blood – brain barrier. This membrane separates the fluid around the brain from the fluid outside the brain [extracellular]. It is very selective in what it allows to enter the fluid surrounding the brain. Maier found that the cytokine molecules released into the blood by the macrophages were too large to cross the blood-brain barrier so there had to be a signal reaching the brain some other way to trigger cytokine release causing a “sick response”.
The body has many nerves as you well know, but what you may not know is there is one particular nerve that extends from the brain to almost every organ in the body conveying vital information about the body to the central nervous system. It is called the Vagus nerve. What Maier discovered was that the cytokine released by the macrophages only served as a messenger. Kind of like a scout. These cytokines locate sites along the Vagus nerve that contain special chemicals called neurotransmitters. These chemicals are designed to literally change a blood borne signal to a nerve signal. Neat huh? It’s all downhill from there, or up, as the signal travels back to the brain triggering cytokine release and the subsequent “sick response”.
Mind Body Connect
Have you ever noticed that when you are in a stressful situation, there is a tendency to be more susceptible to illness? Maier concludes through experimentation on rats that the same type of cytokine chemical [interleukin-1] which triggers a “sick response” with infections also triggers a “sick response” with stress. Those animals exposed too severe social or physical stress exhibited large increases in Interleukin-1. The difference being the point where the trigger occurs. Stress cytokine originates in the brain while infection cytokine originates in the immune cells [macrophages]. So strong is the similarity, that being under a lot of stress may predispose an individual to infection and vice versa. It’s worth noting here that Maier continues his work in Pyschoneuroimmunology attempting to link variations in the immune system to variations in day to day cognitive function.
Could this be why some people are able to cope with or conquer debilitating injuries and illnesses while others do not? Considering these facts, perhaps the ideas of self-healing through the power of positive thinking is not too far off track. Perhaps the power of faith is not just spiritual but in changing the heart and mind one also has the power change the physical. Interesting isn’t it?