Chronic stress is linked to the development of many psychological problems, such as depression, anxiety, and schizophrenia. A large body of research also indicates that stress is linked to a variety of physical problems, including cancer, heart disease, rheumatoid arthritis, genital herpes, periodontal disease, yeast infections, and the common cold, to name just a few.

Stress and Immune Function

Stress affects the functioning of the immune system, as do age, nutrition, and genetic factors. The immune system is the body’s defense against harmful agents such as bacteria, viruses, and other foreign substances. It communicates constantly with the brain and the endocrine system. The immune system has many different kinds of disease-fighting cells, including B lymphocytes, T lymphocytes, and macrophages:

  • B lymphocytes are formed in the bone marrow and release antibodies. Antibodies are protein molecules that travel through the blood and lymph and defend the body against bacteria and cancer cells.
  • T lymphocytes are formed in the thymus gland and defend the body against cancer cells, viruses, and other foreign substances.
  • Macrophages destroy foreign substances by absorbing them.

Stress affects the immune system in many ways. For instance, hormones that are released in response to stress can inhibit the activity of lymphocytes.

The Link Between Emotions and Illness

Researchers have linked negative emotional states to disease.


Recent research suggests that depression makes people more vulnerable to heart disease.

Type A Behavior and Hostility

Researchers have identified a type of personality, called the type A personality, that is associated with a higher risk of coronary heart disease. People with type A personalities tend to be competitive, impatient, easily angered, and hostile. People with type B personalities, on the other hand, are relaxed, patient, easygoing, and amiable.

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