Virtually all Gulf War participants were exposed to a wide range of stressors associated with the war. Throughout human history, observers have noted a correlation between the horrors of war and "mysterious" illnesses in soldiers and veterans.91 Only recently, however, have the broad range of symptoms for such illnesses been recognized as serious, physiological effects of stress.

Unexplained illnesses in soldiers were widely interpreted as a form of malingering until the 1940s. When WWII veterans experienced many of the same symptoms seen in WWI, Charles Samuel Dyers coined the term "shell shock." He began to study and write about what actually happened to the minds and bodies of soldiers on and off the battlefield. Physicians began to describe psychosomatic symptoms-physical disorders caused or influenced by a psychological state-as the normal and expected consequences of experiencing fear and fright, and recognized the relationship between intense emotion and bodily changes.

During this period, a telling example came to light that illustrated how traumatic experience can lead to a decline in physical health. A group of merchant marines in Norway during WWII were preselected for their excellent physical and mental health. Yet after exposure to extraordinary stress, they showed a sharp decline in their health. Many had symptoms of chronic fatigue, chronic pain, impotence, and irritability.

Today, scientists are beginning to unravel the physiological connection between the brain and various other parts of the human body. Recent animal and human studies reveal numerous pathways connecting the brain to the rest of the body, through which psychological stress can be physically expressed.31 Animal studies demonstrate that stress can have measurable effects on the brain, immune system, cardiovascular system, and various hormonal responses. Although the human body can adapt to normal stresses, if the stress lasts longer it can be expressed in a variety of physical illness symptoms.155 Some researchers suspect that the inadequate production of stress hormones and stress response occurs in some (not all) humans with CFS and PTSD.31

Based on this understanding and supported by decades of clinical observations, physicians recognize that many physical, as well as psychological, diagnoses are the consequences of stress. This connection is not limited to soldiers only. Experts now know that conventional stressors, such as bereavement, family problems, financial and job problems, domestic or other violence, can cause significant and long-term physical health effects.76,184

Physicians and scientists also note substantial variability in the human response to stress. One individual's reaction to trauma could be hypertension; in another individual, the reaction to similar trauma might be severe anxiety. A number of medical diagnoses are linked with stress, including somatoform disorders, CFS and FM. These conditions share many overlapping features, and each diagnosis depends on meeting specific case definitions. Significant evidence supports the likelihood of a physiological, stress-related origin for many of these ailments.

The Committee concludes that stress does not cause a unique illness or set of symptoms. Stress can contribute to a broad range of physiological and psychological illnesses. Stress is likely to be an important contributing factor to the broad range of illnesses currently being reported by Gulf War veterans.