WASHINGTON (American Psychological Association) -- Chronic stress not only makes people more vulnerable to catching illnesses but can also impair their immune system's ability to respond to its own anti-inflammatory signals that are triggered by certain hormones, say researchers, possibly altering the course of an inflammatory disease. This finding is reported on in the November issue of Health Psychology, published by the American Psychological Association (APA).

Chronic stress seems to impair the immune system's capacity to respond to glucocorticoid hormones that normally are responsible for terminating an inflammatory response following infection and/or injury, according to researchers Gregory E. Miller, Ph.D., of Washington University and colleagues. To examine what happens to people's immune systems during on-going stressful situations, the researchers compared 25 healthy parents with children undergoing treatment for pediatric cancer with 25 healthy parents with healthy children on measures of mental health, effects of social support and certain immune system responses. All the parents had blood drawn at the initial session and salivary cortisol samples taken at intermittent times over two days.

Parents of cancer parents reported more psychological distress than parents with healthy children, according to the study. The parents of cancer patients also were found to have diminished glucocorticoid sensitivity compared to parents of medically healthy children. This hormone is responsible for turning off the in vitro production of the pro-inflammatory cytokines interleukin-1B , interleukin-6 and tumor necrosis factor, said Dr. Miller. The good news found by the researchers was that social support lessened the immunologic consequences of caring for a child with cancer, perhaps by helping the parents deal with the economic, work and family disruptions caused by the disease and its treatment.

"These findings suggest a novel mechanism through which psychological stress could influence the onset and/or progression of conditions that involve excessive inflammation, like allergic, autoimmune, cardiovascular, infectious and rheumatologic illnesses," Dr. Miller. But even though the cancer patient parents reported more depressive symptoms, depression does not seem to operate as a mediator. It may be that anxiety, intrusive thoughts, feelings of helplessness or lack of sleep may be influencing the stress-related reductions in glucocorticoid sensitivity.

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