BOSTON U.S. combat soldiers in Iraq who received a shot of morphine within an hour of being wounded were less likely to develop post-traumatic stress disorder, researchers reported on Wednesday.
The painkiller injections are no guarantee of preventing PTSD, according to the report in the New England Journal of Medicine, but the findings may help doctors find a better way to prevent the debilitating psychic strain of combat.
"We are not sure if the effect is from pain reduction or from an effect morphine has on memory consolidation in the brain immediately after a traumatic event. Or it may be both working together," Troy Lisa Holbrook of the Naval Health Research Center in San Diego said in a telephone interview.
"We need more research to tease those out and find out which one it is," she said.
PTSD can cause flashbacks, edginess and emotional numbness. The risk depends on the type of traumatic events a person is exposed to. A 1995 survey found that 7.8 percent of the U.S. population was destined to experience PTSD at some point.
"The search for a 'morning-after pill' after exposure to traumatic stress is obviously of great importance," Dr. Matthew Friedman of the National Center for PTSD wrote in a commentary.
The study of 696 members of the Army, Navy and Marine Corps, all wounded in Iraq from 2004 to 2006, found that 61 percent of those who eventually developed PTSD had been given morphine, usually within an hour after being wounded.
But 76 percent of those who did not develop PTSD had been given morphine.
"It did not appear that the severity of the injury made any difference in this observed association," said Holbrook, who added that many other questions needed to be explored, such as whether the dose of morphine makes a difference.
She said her team would be looking at the effects of other opiates and anti-anxiety drugs to see if they work as well, or better.
Thursday's Journal also contains a separate study that looks at the risk of mental health problems among the wives of soldiers who are deployed in combat situations.
It found that depression, sleep disorders and anxiety were significantly more common among Army wives whose husbands had been sent to Iraq or Afghanistan. The medical records of more than a quarter of a million women were assessed.
"I don't think these results will come as a shock. But it's the first study of this size to put actual numbers with these issues," Alyssa Mansfield of RTI International in North Carolina, who worked on the study, said in a telephone interview.
(Editing by Maggie Fox and Peter Cooney)