Dr. Roy Murrell, DC 200 NE 20th Avenue, Suite 140 Portland Oregon 97232 - disclaimer - 971-312-9497
Most everyone has heard of the phrase: "Stress kills". Unfortunately, there is some truth to it. At the very least, it can have a negative impact on many aspects of your health. It is hard to exist in today's world without some sort of stress. Most of us sleep less, work more, vacation less, all the while struggling for some sort of balance between what you want in life and what is realistic. Some say you always have a choice, but it’s often not easy to make positive changes or escape stressful situations. So just how does stress affect us, physically? This is a fascinating subject, and very extensive, so I have decided to write this in two parts (so that I don't cause any stress over the length of this newsletter.) First, let’s take a brief refresher in the physiology of stress hormone.
ANATOMY OF STRESS
We know that our brains control everything by communication through the nervous system. Our nervous systems have two parts: the voluntary nervous system whereby you consciously initiate an action, and the involuntary, or autonomic, system that controls your body functions without your conscious involvement. It is the autonomic system that controls your stress responses.
The autonomic system has two parts, the sympathetic and the parasympathetic. The sympathetic is our "fight or flight” response or one that is activated most by stress. This does not have to be a scary or bad stress; it can be a good stress, such as excitement over a new relationship. When activated, the sympathetic nerves, literally within seconds, release hormones called epinephrine and nor-epinephrine. Sometimes, to our detriment, humans can activate these hormones with just a single thought; you don't need a stressful event, you only need to think about one. The parasympathetic system acts as an opposing system to the sympathetic nerves. It is active during digestion, sleep, and the rebuilding of important molecules such as proteins, hormones, and new cells to replace dying ones. Unfortunately, when your sympathetic system is on alert in a stress response, your parasympathetic system is suppressed. Ever notice how poorly you sleep or how cantankerous your digestion system is when going through a stressful event? If the stress continues for more than a few minutes, your brain sends a message to the adrenal gland to secrete another stress hormone called glucocorticoid. Glucocorticoids belong to the steroid family of hormones, as do testosterone, estrogen, progestins, and mineralocorticoids. They are more responsible for sustained stress. The majority of the research has been done on the effects of glucocorticoids.
THE STRESS RESPONSE
Stress is a very normal and necessary part of our human physiology; we would have not evolved and survived without it. It is only when it becomes a chronic phenomenon that it starts to have a negative impact on our health. This negative impact can reach almost every functioning part of our body from the heart to the reproductive system, mostly through the suppression of the parasympathetic system.
One of the most talked about dangers of chronic stress is heart disease. Although heart disease has recently been replaced by cancer as the leading cause of death in this country, it still comes in a close second with over half a million deaths every year. Stress hormones can play a major role in heart disease risk. Secretion of glucocorticoids stimulates the heart to beat faster. These same hormones cause constriction of the veins that carry blood back to the heart, which increases the blood pressure. The blood reaches the heart with a greater speed and force causing the heart muscle to push back and thus causing the heart not only to beat faster but with more force, driving the blood pressure up even more. If this increase in pressure becomes chronic, it results in irritation of the lining of the blood vessel walls, especially at points of bifurcation where vessels branch off. This irritation or inflammation becomes a collection point for molecules of fat and sugar that have been mobilized as part of the stress response. These collections are known as plaques and if they get large enough, can occlude the vessel stopping all blood flow. If this vessel is in the heart muscle, you have a heart attack. This increased pressure also leads to a thickening of the walls of the arteries thus making them more rigid (commonly called hardening of the arteries) and further increases pressure in a vicious cycle. The heart muscle eventually fatigues from this overwork and that can lead to congestive heart failure. If you throw in a diet rich in trans-fats and inflammatory omega-6 fats (which is most of what Americans eat), no exercise, and a side of obesity, you can put this whole process on a fast track to disaster.
Of course, all this is preventable. We will talk more about techniques in reducing stress later on.
THE IMMUNE SYSTEM
Most people are aware that when their stress levels are very high they tend to be more vulnerable to illness and that is not a coincidence. When your body is pumping out stress hormones to prepare you for escaping a tiger that is about to have you for dinner, fighting off a virus is the last thing on the agenda. Most of the scientific research has focused on the effects of glucocorticoids on the immune system. What they found is that these stress hormones shrink the Thymus glands which are responsible for the maturation of T-cells, sometimes called killer cells. T-cells are the main vehicle of our cell-mediated immunity. They are produced in the bone and are responsible for recognizing and destroying foreign elements such as bacteria or viruses. (It is the T-cells that are destroyed by the AIDS virus which leaves AIDS patients vulnerable to serious life threatening diseases.) Glucocorticoids halt the formation of new lymphocytes (white blood cells) in the thymus, and most of the thymic tissue is made up of these new cells, ready to be secreted into the bloodstream. They also inhibit the release of interleukins which are messenger-type molecules that alert other parts of the body to the presence of an invader, resulting in an immune system that is less responsive to an infection.
Autoimmune disease is an increasingly common diagnosis in this country. The most common autoimmune problem is inflammatory in nature and is caused by the immune system getting activated by something in the environment and then failing to shut down. Eventually it starts attacking your own tissue because it does not differentiate between what is "you" and what is "not you". No one really knows why this happens, but a standard, time-honored treatment for these conditions is to give the patient massive doses of synthetic glucocorticoids for the purpose of suppressing the immune system from attacking itself. It has been well accepted that when there is prolonged exposure to glucocorticoids (stress hormones) there is a suppression of the immune system. That being said, it is still scientifically unclear whether prolonged stress actually increases your risk to serious illness such as cancer. There have been studies that indicate stress does influence how well or successful you recover from cancer but it is less clear whether it predisposes you to increased risk of a cancer diagnosis. What we do know and can say for sure is: prolonged stress compromises your immune system and in the end it is the immune system that really keeps us healthy.
STRESS AND PAIN
Most of the research in this area has been focused on acute stress (as opposed to chronic long term stress). Everyone has probably experienced, or has known someone who has experienced, an accident in which they were injured but did not feel the pain of that injury due to the intensity or stress of the situation. This is known as stress-induced analgesia. It is also felt frequently in the course of exercise; you start off on a run and everything hurts but as you hang in there, your body begins to feel almost euphoric and this is not your imagination. The body, under stress, produces three compounds with chemical structures similar to opiate drugs (our most potent pharmaceutical pain killers). They are enkephalins, dynorphins, and the most famous of them all, endorphins. These are known as endogenous morphines or Opioids. They are produced and released by parts of the brain that regulate pain perception. The receptor sites in the body that bind these pain reducing Opioids are the same receptor sites that bind opiates such as morphine and heroin. You have heard of being addicted to exercise; it can happen!
So what happens when there is chronic long term stress? There is such a thing as stress-induced hyperalgesia (increased pain perception). This does not involve more pain perception, and has nothing to do with pain receptors in the spinal cord. Instead, it involves a more emotional reactivity to pain, interpreting the same sensation as more unpleasant. Brain studies have revealed that it is the more emotional part of your brain that cause this hyperalgesia, the parts of the brain that are the core of our fears and anxiety. It is common that people who are prone to anxiety also complain of frequent musculoskeletal pain. I see this variation in pain perception almost daily in my practice.
Where does the diagnosis of Fibromyalgia fit into all of this? Many think this is a psychosomatic illness but research has shown that these patients have high levels of activity in parts of the brain that mediate the emotional/contextual assessments of pain, the same areas activated in stress-induced hyperalgesia. In addition, their cerebral spinal fluid contains excess amounts of a neurotransmitter that mediates pain (called substance P). It is possible these patients have an abnormal regulation of stress hormones but no one really knows at this point.
THE CONNECTION OF STRESS, FOOD, AND DIGESTION
Stress and appetite are sort of a mixed bag. Acute, intense stress is most always an appetite suppressor. However, for someone with an ongoing chronic or even episodic glucocorticoid stress, eating becomes a hobby. To make things worse, glucocorticoids stimulate cravings for high carbohydrate and high sugar content foods. To add more insult these hormones trigger the fat cells in the body to secrete an enzyme that facilitates the storage of this mass sugar consumption as new fat cells around your waist. This whole process can vary of course; people who frequently use food as a comfort or reward are more prone to this than those who have a healthier relationship with food.
Another component to stress and food is perhaps the most significant: digestive dysfunction. I talked earlier about the parasympathetic nervous system being responsible for digestion and how the secretion of stress hormones stimulates the sympathetic system and suppresses the parasympathetic system. This suppression is thought to be the major factor in what is called "functional GI disorder". The most common one is IBS or Irritable Bowel Syndrome. IBS consists of an array of symptoms including gas, constipation, bloating, diarrhea, and abdominal pain. IBS is often referred to as "a spastic colon" because the colon has become too contractile. The colon is a muscle that contracts to move waste through the system. If it contracts too much, it can move things too fast before the water in the system can be reabsorbed, leading to diarrhea. If the condition is prolonged, the contractions can become disorganized leading to constipation. The cramping, bloating, gas, and pain are bi-products of this activity. Is stress the sole cause of IBS? Probably not, but most scientists feel it plays a significant role.
By far the most common association of stress and the digestive tract would have to be the subject of ulcers. When most people hear the word ulcer, they think of stress. It wasn't until 1983 that a scientist discovered that the vast majority of ulcers (and we are talking peptic here) are caused by a bacteria called Helicobacter pylori. It is estimated that close to 100% of the population are infected with this bacteria so it stands to reason that there are other factors in the pathology of ulcers and you guessed it, stress is one of them. Others include lifestyle issues such as smoking, alcohol, pain medication, and diet. With controls for other factors, it is estimated that stress causes a two to three-fold increase in the risk of an ulcer. The mechanism is somewhat complicated. For many years, it was thought to be too much acid and it turns out that acid is involved but more in the recovery stage of a stressful event as opposed to the actual event. During the height of any stress period, we actually have a decreased acid production (the body is not interested in digesting food when you are dealing with a crisis). When acid is not being produced the stomach lets down its defenses (meaning the mucous production that coats the lining of the stomach walls to protect them from the acid; you don't want your stomach acid digesting the walls of your stomach). That is all fine until the stress is over and acid production comes back on line which can then cause an irritation to the walls of the stomach. This, along with the Helicobacter Pylori that is most always present, and a few too many doses of NSAIDs like Advil or aspirin and an ulcer is the result.
Stay tuned for more on this subject in my next letter where I will talk about Stress and Memory, Sex and Reproduction, Sleep, and Depression. I will also touch on some tips on how to reduce your stress short of quitting your job and living on a tropical island.
Yours in Health