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Psychoneuroimmunology   Have you heard about the new field of psychoneuroimmunology? Scientists in this field of study try to evaluate the effects of psychosocial stress on the immune system. In the 1970's when I was in medical school, those two domains were thought to operate separately. At that time, it was thought that the immune system made antibodies, mediated tissue repair, killed viruses and bacteria as well as tumors. The brain was responsible for figuring out complex math problems, solving puzzles, inventing new tools and telling our bodies how to dance like RC Hammer. Now there is strong evidence that the autonomic nervous system communicates through nerve connections to tissues that form and store many of the cells of the immune system. Once activated, these tissues send various cells into the circulatory system to carry out their innate immune function. Another fascinating discovery is that the tissues of the immune system have receptors for all of the hormones released by the pituitary gland which is located in the mid-brain. Essentially these tissues are sensitive to brain function.   If someone is highly allergic to roses and you wave a silk or plastic rose in front of them, they will react as if the rose was real. They will have an allergic reaction. Studies at UCLA showed that when professional actors spent a day either performing a depressing, negative scene or an uplifting, positive scene, their immune system's responsiveness were decreased or increased respectively. If you are having a bad day, your immune system decreases its effectiveness. If you are having a good day, your immune system responds much better.   One of the most important studies in the field of psychoneuroimmunology was one that used a method referred to as a conditioned immunosuppressive paradigm. The gist of these studies is rather simple. The first step is to give an animal a drug that suppresses the immune system. At the same time, give the animal a conditioned stimuli like an artificially flavor drink that the animal will associate with the suppressive drug. A few days later, only just give the artificially flavored drink to the animal - down goes their immune function.   In 1982 Robert Ader and Nicholas Cohen stunned scientists when they reported their results of an experiment that used a variant of the conditioned immunosuppressive paradigm. These two scientists used a strain of mice that spontaneously develop disease due to over activity of their immune systems. The standard approach for treatment of the disease that develops in these mice is to use an immunosuppressive drug. Ader and Cohen showed that by using their conditioning techniques, they could substitute the conditioned stimulus for the actual drug and the mice's immunity was altered enough to extend their life spans when compared to untreated controls.   Without question, there is a strong link between the central and peripheral nervous systems and immune function.   What does an artificial rose or the taste of an artificially flavored drink have in common with our daily living habits? Everything! If a plastic flower or a diet soda can alter your immune system, so can stress. It's the ultimate conditioned immunosuppressive variable. How does this happen? It is complicated.   There is no doubt that during an isolated episode of extreme stress, the immune system helps all of us respond favorably to the emergency. Once the acute stress has passed, we recover and move on. But in sustained stress, there is a chronic suppression of the immune system that results in the impairment of our bodies to fight infection. Constant unrelenting stress may also cause autoimmune diseases to flare, cancer treatments to be less effective, and increase the risk and severity of some diseases. But we must be cautious about making conclusions about stress and illness since the connections are probably relatively weak and its importance in disease as a whole is often exaggerated. Connecting the two is awfully lucrative in a consumer driven medical economy like ours is in America.   The best way to approach this subject is to break it down into small bites of information. Over the next few weeks, I will try to explain immune function in simple and accurate terms. Then I will discuss how stress may inhibit immune function and afterwards, try to explain chronic stress and disease risk. So sit back, take a deep breath and relax. It's probably good for you and your immune system at the same time.   Doc
Posted by Amanda Sanders at 9:09 AM
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