Stress and Heart/Cardiovascular Disease
The stress response is most maladaptive in the heart and cardiovascular system because it causes the whole system to work harder. With repeated stress, the heart and blood vessels wear out.2 This occurs most often where arteries branch, due to turbulence of the blood at branching.2 The smooth inner lining of the vessel begins to tear, scar, and pit. Fatty acids and glucose in the blood, mobilized by the stress response, begin to work their way under the lining of the blood vessel, stick there, and cause thickening.2 In addition, epinephrine causes fatty nutrients to form and makes the blood thicker and more likely to clot.2 The blood vessels start to clog up and blood flow decreases. This result is called atherosclerosis, which is a demonstrated result of chronic stress in several species, including humans.2
Once the cardiovascular system is damaged, it is extremely sensitive to stressors, either physical or psychological. Stress can cause the sympathetic nervous system to send two symmetrical signals to the heart that cause it to misfire.2 Sudden joy or grief has a similar effect on the cardiovascular system.2 This is not true for the reproductive system, the growth system, or the immune system.2
A recent review of studies published between 1970 and 2004 found convincing proof that extreme physical exertion (particularly in individuals not accustomed to exercise), psychological stress, anger, and over- excitement can lead to chest pain, heart attack, and sudden cardiac death in those at risk for heart disease.7 These studies differ from previous ones that assess risk factors for developing cardiovascular disease such as inactivity, cigarette smoking, chronic stress, and anger. The new studies identify sudden, acute changes that appear to precipitate heart attacks in an already susceptible population of patients.7
Individual differences account for much of the risk of cardiovascular disease:2, 8
1. An already damaged cardiovascular system.
2. Genetic factors influencing the mechanics of the system such as the elasticity of blood vessels and the
number of norepinephrine receptors.
3. Smoking, high blood pressure, or high triglyceride levels.
4. Personality (specifically Type A, hostile or angry).
Scare tactics have little effect on changing old habits, so it is best to discuss the choices that can be made to promote wellness and health. Research has shown that making modifications to lifestyle, including exercise and diet, can actually cause arteries to become less blocked! This is something that was previously not believed to be possible.4 Heart bypass and angioplasty surgeries, in addition to being horrendously expensive, have not proven to be effective in increasing life expectancy in most cases. However, changes in exercise and diet have reversed the damage to the cardiovascular system, and have
improved health and wellbeing.4 Coping with both lifestyle and emotional stress can reduce the risk of cardiovascular disease, especially for the Type A personality.4, 2 This will be discussed in our third article.
Stress and Diabetes
Type 2 (adult-onset) diabetes is the result of the body’s response to inactivity and a surplus of fat. It is a common problem in Western populations. There is no increased risk of this disease in non-westernized populations. With diabetes, the body becomes resistant to insulin, the hormone that tells the body to convert circulating fats, proteins, and sugar into fat and protein. If enough fat is stored and the fat cells are full, they become less responsive to the insulin. The cells lose their specialized receptors for insulin. There is too much circulating glucose and fatty acid that damage the kidneys, blood vessels, and eyes. The stress response causes even more glucose and fatty acids to be mobilized in the bloodstream. It blocks insulin production and it promotes insulin resistance. Chronic stress can cause atheroscelerosis in someone who is already insulin resistant or borderline diabetic due to the increase of circulating fatty acids and glucose.2
Type 1 (juvenile) diabetes is insulin-dependent diabetes.2 The immune system attacks the cells of the pancreas that secrete insulin, so the person has a reduced capacity to produce insulin. With reduced insulin, there is little capacity to store excess glucose and fatty acids, so cells starve while there is excess circulating fatty acids and glucose in the bloodstream.2 These clog the kidneys, form atherosclerosis in the blood vessels, and link proteins in the eyes, causing cataracts.2 Stress aggravates Type 1 diabetes.
15% of people over 65 in the U.S. have insulin-resistant diabetes. The disease more than doubles mortality and nearly triples the rate of heart disease in men. It is the leading cause of blindness and the 7th leading cause of death.2
Even without diabetes, stress causes mobilization of energy sources. Shuttling nutrients in and out of the bloodstream costs energy, so if you are stressed frequently, you will tire more easily and experience regular fatigue.2
Stress and the Digestive System
The digestive system quickly shuts down during stress.2 The first noticeable sign is a lack of saliva and dry mouth. Chronic stress results in diseases of the digestive system.
Ulcers are still not well understood, but the discovery of the bacteria Helicobacter pylori has lead to the understanding that this bacteria is a predisposing factor in ulcer formation.2 However, since most people have this bacteria in their digestive systems, it cannot account for all ulcers.2 Approximately 10% of the people infected with the bacteria develop ulcers.2 15% of duodenal ulcers form in people with no Helicobacter infection.2 So, there must be at least two factors acting together, such as non steroidal anti inflammatories (eg. Aspirin), a genetic tendency to secrete too much acid or to secrete insufficient mucus to protect the stomach lining from acid, or ....stress.2 Many studies have shown that people who are anxious, depressed, or undergoing severe life stressors are more likely to experience duodenal ulcers.2 It has been shown that a little stress with tons of bacteria OR lots of stress with just a little bacteria will cause an ulcer.2
The link between stress and irritable bowel syndrome has not been successfully proven because it is very difficult to study and document. However, it is fairly well recognized that chronic stress worsens existing cases of gastrointestinal problems including colitis for some people.2
The effect of stress on appetite is still being researched, but we do know that two opposing systems are activated when a stressful event occurs. Corticotropin and Corticotropin releasing factor, hormones released in the stress response, suppress appetite for the short term. Under longer episodes of stress, these hormones are probably released for a longer period of time. Glucocortoids are also released. They are slower acting and stimulate the appetite.2 Presumably this system works for the immediate physical threats requiring the fight-or-flight response (i.e., lose appetite at first but then get hungry to replenish the energy expended once the event has passed).2 The different parts of the system work together, one for the immediate response and one for the recovery.
Stress and Cancer
There is no conclusive evidence that stress either leads to a greater incidence of cancer or that existing cancers progress more rapidly. Some sources claim a higher risk of cancer with stress 5, but scientific research with humans has not proven this.11, 12, 13 There appears to be a link between personality type and increased cancer risk, but lifestyle variables were not ruled out in this research.2 Conforming, compliant people are somewhat more prone to cancer, but they may also have a higher incidence of smoking, drinking or fat consumption which may account for this increase in cancer risk.2 One study has found that severe life stressors cause a small, but significant increase in breast cancer in women, though medical experts still do not agree whether stress alone contributes to the incidence of cancer development since the issue is generally confounded with other complex lifestyle and genetic variables.14
The most harmful theories about cancer are those professing that with enough courage, spirit, and love, cancer can be prevented or cured.2 In the case of childhood cancer, it is implied that the parents are at fault because they are not providing a sufficiently nurturing environment. Everything bad in human health is not caused by stress and it is negligent to imply that we can cure ourselves of cancer by thinking healthy thoughts.2
Stress-induced pain relief
The body synthesizes three different classes of opoid compounds: enkephalins, dynorphins, and endorphins.2 Release of these compounds in stressful situations is shown to occur on the battlefield, in sports, and in everyday exercise programs.2 After about 30 minutes of exercise, endorphins are released, masking sensations of pain, causing a “runner’s high”. Many other types of stressors including surgery, low blood sugar, exposure to cold and childbirth, produce similar effects. 2,15 From an adaptation standpoint this makes sense when one must run from the enemy or fight despite injury. With prolonged exposure to stress, however, the body’s supply of opoids runs out and the sensation of pain returns. There appears to be no stress-related disease that results from excess opoid release.2