By LEE BOWMAN
Scripps Howard News Service
December 06, 2005
Psychological stress and physical ills have become so well linked over the past few decades that researchers into the brain-immune system connection have a name for the specialty - psychoneuroimmunology.
Two studies published Monday further illustrate when and how stress impacts the immune system.
A report in the Archives of General Psychiatry finds that routine marital discord can slow the body's ability to heal from trauma or surgical wounds by as long as two days. The second study, by Australian researchers working with mice, fingered a specific stress hormone that appears to disrupt the work of immune cells.
In the first study, a team at Ohio State University led by Jan Kiecolt-Glaser, a professor of psychiatry and psychology, and her husband, immunology professor Ronald Glaser, found that married couples who showed high levels of hostility to each other needed two days longer to heal from wounds compared with couples whose hostility levels were low.
Even typical married couples who argue for just a half hour slow their ability to heal from wounds by about one day.
The researchers, who have been doing stress-immunity work for 30 years, have mainly focused on the effects of long-term stressful events, like caring for a spouse with Alzheimer's disease or students subjected to days of exam-taking. In this case, the stressor was a staged "marital discussion" that lasted only a half hour.
"The fact that even this can bump the healing back an entire day for minor wounds says that wound-healing is a really sensitive process," Kiecolt-Glaser said, noting that the effect is powerful enough for hospitals to consider looking at stress-reduction interventions for patients before surgery.
The experiment involved 42 married couples who had been together an average of at least 12 years. Each couple made two, 24-hour visits to the university's clinical research center, with two months passing between visits.
During each visit, both partners were fitted with a small suction device that created eight tiny blisters on their arms, which were then monitored for evidence of healing.
Husbands and wives also completed questionnaires designed to gauge their level of stress at the beginning of the experiment. During the first visit, each spouse was asked to talk about some characteristic or behavior he or she would like to change in a partner, in a supportive, positive discussion.
"But during the second visit, we asked them to talk about an area of disagreement, something that inherently had an emotional element," Kiecolt-Glaser said. Tapes of both discussions were used to gauge the levels of hostility.
"The wounds on the hostile couples healed at only 60 percent of the rate of couples considered to have low levels of hostility," Kiecolt-Glaser said.
Blood tests also showed that levels of an immune-system regulator that can cause inflammation was 1-1/2 times greater in the most hostile couples compared to those rated for the least hostility.
In the Australian study, researchers from the Garvan Institute of Medical Research in Sydney focused on another immune-system regulator, a hormone called neuropeptide Y (NPY), that normally activates and shuts down the immune system as needed to fight infections.
"But during periods of stress, nerves release a lot of NPY and it gets into the bloodstream, where it directly impacts on the cells of the immune system," said Fabienne Mackay, lead author of the study published in the Journal of Experimental Medicine.
"Under normal conditions, circulating immune cells produce small amounts of NPY," which allows them to be on alert for invaders and to summon the killer immune cells from lymph nodes if an infection is found. But a jolt of NPY is also used by the immune system to shut down those cells so they don't run amok in the body after doing their work.
"Too much NPY means that the attack is prevented despite the foreign invaders being identified, and this is what happens during stress," Mackay said.
The findings offer prospects for new treatment in people whose immune systems are suppressed, as well as for people whose immune responses turn against them in diseases such lupus, rheumatoid arthritis and multiple sclerosis.
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