Having finished our discussion of the various factors that cause people to experience stress in positive, negative or neutral forms, we are now in a position to talk about the potential problems that can develop when people are faced with repetitive distress. Chronic and persistent negative stress (distress) can lead to many adverse health problems, including physical illness, and mental, emotional and social problems.

The Physical Impact of Stress:

The immune system is a complex group of cells and organs that defend the body against disease and infection. A healthy immune system remains in homeostasis (balance), much like the speeding up and slowing down relationship between the sympathetic and parasympathetic nervous systems that we described previously in the section of this document concerned with the fight-or-flight response. Because of this similarity, the immune system has sometimes been called our "liquid nervous system."

Stress causes these cells and organs that compose the nervous system to release hormones that trigger the production of white blood cells (which fight infection) and other disease-fighting elements. This stress-triggered hormone release is essential for priming the immune system to respond quickly to injuries and acute (short-term) illnesses. However, this activity is not beneficial to your health if it continues for more than a short while. Chronic stimulation of the immune system causes the system to become suppressed overall, and thus become less effective at warding off diseases and infections.

Researchers have learned that cells in the immune system release chemicals called cytokines that act as messengers. These messengers allow cells to "talk" to one another and instruct each other to develop additional cells to fight infection. Hormone release during chronic stress may inhibit the production of cytokines, thus thwarting the body's ability to effectively coordinate the fight against infection. Because of this reduction in cytokines, the immune system's proliferative response (its ability to successfully fight off disease) decreases by 15% or more during chronically stressful situations. It is not surprising then, that individuals who are highly stressed are more likely to succumb to colds, infections, and herpes breakouts (a viral infection that causes infected people to develop sores on their mouths or genitals).

The breakdown of communication between the various aspects of the immune system that occurs during times of chronic stress may also be responsible for triggering flare-ups (or new cases) of various autoimmune diseases such as Crohn's disease, psoriasis, rheumatoid arthritis, lupus, multiple sclerosis (MS) and other similar conditions. An autoimmune disease is one where the immune system gets confused, and starts attacking the body's own healthy cells instead of what it should be doing, which is attacking foreign disease-causing bodies.

After stressors (such as injury or illness) have been dealt with, the immune system normally secretes additional hormones that trigger a decrease in the production of white blood cells, enabling the system to rest and rejuvenate itself. This normal decrease and rejuvenation response becomes delayed during times of chronic stress.

Stress and Illnesses

Because of their effects on the immune system, as described above, stress hormones impact the development and severity of many different diseases and bodily systems. In some instances, stress causes existing conditions to worsen. In other cases, stress seems to be a major factor creating vulnerability to developing new conditions in the first place. In the sections below, we explore the contributions of chronic stress to various common medical problems.

Digestive system

Many people experience a stomachache or diarrhea when they are stressed. The stress hormones that slow the release of stomach acid and the emptying of the stomach (in preparation for the flight or fight response) also stimulate the colon so as to quickly empty the digestive system. Sometimes this emptying process results in pain or diarrhea. These hormones can also cause excess belching, farting and other gas problems, and enhance a person's vulnerability to developing Crohn's disease, which is an ongoing inflammation of the membrane lining the colon (the large intestine or bowel). For more information on Crohn's Disease, please visit our Crohn's Disease Topic Center

Chronic stress-hormone induced physical changes can also increase people's appetite, causing them to gain weight and potentially, to become obese. Obesity puts individuals at risk for developing other health problems such as diabetes, heart disease, strokes, and arthritis. Chronic stress may also alternatively cause people to lose their appetite and to lose too much weight.

Cardiovascular system

Chronic activation of stress hormones can raise your heart rate, cause chest pain and/or heart palpitations (sensations that your heart is pounding or racing), and increase your blood pressure and blood lipid (fat) levels. Sustained high levels of cholesterol and other fatty substances in the blood can lead to atherosclerosis, a disease in which fatty plaques build up on blood vessel walls, restrict blood flow to the heart and sometimes lead to a heart attack.

Cortisol levels also appear to play a role in the accumulation of abdominal fat, which gives some people an "apple" shape. People with apple body shapes have a higher risk of heart disease and diabetes than do people with "pear" body shapes, where weight is more concentrated in the hips. Some very new research suggests that people with apple-shaped bodies are also at increased risk for developing dementia of the Alzheimer's type in later life than are people with pear-shaped bodies. For more information on dementia, please see our Alzheimer's Disease and other Cognitive Disorders.

The relationship between stress and heart health can also be a bit more indirect. People who respond to stress with anger or hostility have an increased risk of developing cardiovascular disease. Similarly, unhealthy stress coping strategies such as smoking, drinking, or overeating can also damage the heart and surrounding blood vessels. For more information on heart disease, please see our Heart Disease topic center.

Musculoskeletal System

Stress often causes muscles to contract or tighten. Over time, sustained stress can cause aches and pains to occur due to muscle tension. Many people experience muscle spasms in their neck and shoulders as well as their lower back. Stress can also cause (or exacerbate) muscular twitches and uncontrolled movement (tics); headaches due to muscle tension; migraines (headaches due to changes in nerves and blood vessels that can cause severe pain, nausea, and sensitivity to light and sound); and tempromandibular joint dysfunction (TMJ) which involves pain in the jaw at the joint site where the lower jaw joins the skull.

Reproductive System

The hormones accompanying stress can cause reproductive problems for both women and men. Women may experience menstrual disorders (such as pain or heavy bleeding), or recurrent vaginal infections. Men who are stressed may develop erectile dysfunction or problems with premature ejaculation during intercourse. Both genders may experience a decrease in sexual desire and/or problems with infertility as a result of stress.

Other Physical Problems

Stress worsens many skin conditions - such as psoriasis (an autoimmune condition characterized by raised, red patches on various parts of the body which may be covered with a silvery white buildup of dead skin cells), eczema (characterized by dry, red, extremely itchy patches on the body), hives (raised, often itchy, red welts occurring on the surface of the skin), and acne. Stress can also contribute to hair loss and some forms of balding; a dry mouth and mouth ulcers; asthma attacks; and an increased risk for having strokes (due to decreased heart health).

Scientists are also exploring the role of stress in creating vulnerability to cancer. The question of whether there is a link between stress and cancer has puzzled and intrigued researchers and patients for many years. Currently, the available research (based on many studies) suggests no consistent relationship exists between stress and vulnerability to developing cancer. There is also no good evidence to suggest that people who repress, suppress, or deny their emotions are more vulnerable to developing cancer, or that there is a "cancer personality type."

This is not to say that there is no relationship between stress and cancer, however. Available evidence does suggest that people's stress levels can influence the course (or spread) of their cancer. For example, one study found that people diagnosed with malignant melanoma (the most serious form of skin cancer) who were in a stress-management group developed better coping skills, improved their negative moods, and experienced fewer relapses of melanoma compared to control patients who did not receive this type of stress management training.

Even though stress does not appear at this time to be a direct cause of cancer, it does seem to impact the development of cancer indirectly, in a similar manner to how stress and cardiovascular disease are related. People who are stressed often use unhealthy coping methods (such as smoking and drinking excessively) to alleviate their discomfort. These unhealthy behaviors clearly increase people's risk of developing cancer.