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The variety of ways in which stress can kill is astounding -- it can lead to heart attacks, diabetes, even certain cancers. Stress can also exacerbate osteoporosis, arthritis and allergies, said noted stress researcher Janice Kiecolt-Glaser, PhD, at APA's Annual Convention.

"If stress doesn't kill you, it will at least make you wheeze," she said.

Research by Kiecolt-Glaser, a psychology professor at the Ohio State University College of Medicine, suggests that while stress's outcomes are diverse, it often affects us through a common pathway: chronic inflammation. By putting the body in a constant state of high alert, this inflammation increases our response to nonthreatening allergens while reducing our ability to heal wounds or respond to infection, she said.

Math anxiety

In the United States, around 30 percent of adults and 40 percent of children suffer from allergies, a hyperactive immune response to otherwise harmless irritants such as pollen and peanut butter. New, yet-unpublished research by Kiecolt-Glaser and her colleagues suggests that this response can be heightened by a single instance of social stress.

In the study, people with seasonal allergies faced a highly stressful situation in which they gave a speech in front of an impassive panel. The panel then asked the participants to quickly count down from a large number in increments of 13; a panel member said "error" in a monotone whenever participants tripped up.

After that test, the participants took an allergy skin test, and their skin immediately puffed up twice as much as the control group's.

"Even skin tests the day after the stressor showed the continuing impact of the stressor on more anxious people," she noted.

The results, said Kiecolt-Glaser, dovetail with past research showing that people with anxiety disorders are more likely to also have asthma and that stress can intensify asthma attacks.

Marital strain

The heightened inflammatory response caused by stress can lead to much graver consequences than itchy eyes. In fact, it can age the immune system, leading to cardiovascular disease, cancer, periodontal disease and frailty, according to research by Kiecolt-Glaser, published in the 2003 Proceedings of the National Academy of Sciences (Vol. 100, No. 15).

In the study, Kiecolt-Glaser and her colleagues followed 225 participants over six years and tested their blood for interleukin-6 (IL-6), a "messenger" protein that promotes cells' inflammatory response. They found that as people age, they produce more IL-6, but that increase is especially pronounced in people who are caring for an ailing spouse.

"Stress made 55-year-olds have 90-year-old immune systems," she said.

The results fit with past research by Kiecolt-Glaser that shows chronically stressed adults are slower to heal from wounds and respond to vaccinations.

Even a single argument can slow the immune response. In a study published in the Archives of General Psychiatry (Vol. 62, No. 12), Kiecolt-Glaser and her colleagues prompted married couples to squabble and then gave them blister wounds.

"The blister wounds for those couples healed more slowly when they were hostile or more nasty to each other following a disagreement," Kiecolt-Glaser said.

By sampling the blister fluid, the researchers found that the stressed participants showed a suppressed immune response compared to a calm control group. In particular, they had little IL-6 at the site of the wound, even though blood tests showed elevated IL-6 in their bodies.

In all, Kiecolt-Glaser's research suggests that social stress puts the body on high alert, but it doesn't prepare us to handle acute, physical stress. What's more, chronic inflammation caused by stress actually wears down the immune system -- which can be deadly.