When doctors diagnose a patient's mysterious pains, sudden sleep difficulties, changes in eating habits, inexplicable migraines or excessive fatigue as psychosomatic, it is easy to apply the layman's translation of "It's all in your head." However, when it comes to these responses to stress, what may be "all in your head" might have a direct impact on what is going on in your body.

With such symptoms as those just described, it is clear that stress, immune function, and depression are linked. For example, those suffering from posttraumatic stress disorder report high levels of depression. Additionally, while you will not find a doctor ordering extensive lab tests to diagnose depression, high levels of cortisol and other stress hormones are found in the blood of the depressed. Also, survivors of early life stress, such as childhood abuse, experience changes in the neurobiology of the brain, making them more vulnerable to depression later in life. Even acute life stressors are known to provoke depression, especially in an environment of poor social support and frequent life crisis. Finally, chronic stress results in lowered immune function and increased incidence of depression. Not only do the relationships between the brain, stress, immune function, and depression exist, but they are bidirectional and complex.

For this Discussion, review this week's Learning Resources as well as the "Stress, Depression, and the Immune Response" section of the "Stress, the Immune System, Chronic Illness, and Your Body" handout. Then reflect on the different ways stress, the stress response, and depression are connected. Finally, consider what part depression plays in the immune and inflammatory response systems.