(Associated Press) -- Quickly giving morphine to wounded troops cuts in half the chance they will develop post-traumatic stress disorder, according to a provocative study that suggests a new strategy for preventing the psychological fallout of war.

Researchers at the U.S. Naval Health Research Center led the study of about 700 troops injured in Iraq from 2004 through 2006.

"It was surprising how strong the effect of the morphine was," said study leader Troy Lisa Holbrook, an epidemiologist at the naval center. The findings were published in Thursday's New England Journal of Medicine.

Whether the Pentagon will adopt the practice on the battlefield remains to be seen. Dr. Jack Smith, acting deputy assistant secretary of defense for clinical and program policy, said in an e-mail that the "very interesting findings" are "likely to stimulate further research."

About 53,000 troops returning from Iraq and Afghanistan have been treated for PTSD, a disorder in which someone who has endured a traumatic event keeps re-experiencing it and the fear it caused. Patients often have trouble with work, relationships, substance abuse and physical ailments.

Researchers have been testing ways to treat it, and the new study looked at whether fast and strong pain relief can help prevent it.

It was unclear whether it was the fast pain treatment or something specific to morphine that made the difference.

But researchers theorize that simply easing pain might reduce the severity of the psychological trauma, or that prompt relief might alter the way the brain remembers the attack or injury -- in essence, causing the mind to file away the episode as less traumatic.

Troops in the study initially were treated at military medical facilities in Iraq, mainly for wounds caused by roadside bombs, bullets, grenades or mortar fire. A few dozen had burns or were hurt in crashes or falls. The decision on whether to give morphine was up to the individual doctor, based on the patient's condition.

Of the 696 troops in the study, 493 -- about 70 percent -- were given morphine, most within an hour of injury. Two years later, 147 of them had developed PTSD. Of the 203 not given morphine early on, 96 developed PTSD.

That worked out to a 53 percent lower risk of developing PTSD for those treated early with morphine. No other factor, such as the nature or severity of injuries, had much effect on the chances of developing PTSD, Holbrook said.

"These are provocative and thought-provoking findings that should lead scientists to investigate the underlying mechanisms" in future studies, said JoAnn Difede, a PTSD researcher at New York-Presbyterian/Weill Cornell Medical Center.

Difede and Barbara Rothbaum, who heads the Trauma and Anxiety Recovery Program at Emory University School of Medicine, said that until more research backs up the findings, the study probably won't lead to many more patients in civilian emergency rooms getting morphine.

"At this point, I don't see it having a huge impact" for civilians, Rothbaum said.

A second study in the journal found that Army wives were more likely to develop depression or sleep problems the longer, or the more times, their spouses were sent to Iraq or Afghanistan.

That study, by researchers at the University of North Carolina and elsewhere, examined medical records for outpatient care of about 250,000 wives of active-duty soldiers from 2003 through 2006.

Compared with wives whose husbands stayed home, those whose husbands were deployed for up to 11 months were 18 percent more likely to be diagnosed with depression and at least 20 percent more likely to be diagnosed with sleep disorders, anxiety and acute stress.

For wives whose husbands were deployed for more than 11 months, problems were even more common: They were at least 24 percent more likely to be diagnosed with depression or anxiety, and about 40 percent more likely to be diagnosed with acute stress or sleep problems.

The researchers didn't have data showing whether husbands were deployed or at home when the wives were being treated for mental health problems.

That meant the scientists couldn't conclude whether those problems were caused by worries about the spouse's safety and the difficulties of being a single parent, or by stress caused by the returning spouse's psychological problems or other behavior changes.

"I suspect that if you look at the Reserve and National Guard wives, the toll might be even worse," because they have less social support than families living in a military community, Rothbaum said.

She said the effects of deployment on children also need to be studied so the military can figure out how to provide more help to families.

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