The Washington Post

WASHINGTON — More than 200 years after it was isolated from poppies, morphine remains one of medicine’s best painkillers. But that isn’t its only use.

Physicians sometimes include morphine in a cocktail of drugs given to people having heart attacks. It can relieve the breathlessness of pulmonary edema. It decreases diarrhea. A famous physician of the early 20th Century, William Osler, once called morphine “God’s own medicine.”

Research published this week suggests the compound may have at least one more use, too.

In a study of about 700 members of the military wounded in Iraq, those who got morphine soon after their injuries were about half as likely to develop post-traumatic stress disorder (PTSD) as those who didn’t get the drug.

Whether morphine’s apparently protective effect arises directly from the relief of traumatic pain, or indirectly by blocking the establishment of traumatic memory, isn’t known.

Both the researchers and outside experts agreed effect would have to be proved virtually beyond doubt before morphine was routinely given to prevent the mental disorder.

“I would be very reluctant to suggest any change in clinical practice,” said Troy Lisa Holbrook, of the Naval Health Research Center, in San Diego, who headed the study published in the New England Journal of Medicine. “We need to understand a great deal more how this appears to work.”

Morphine has been used for pain relief from war wounds since the Civil War. Since World War II, medics and hospital corpsmen have carried small injectors prefilled with the drug.

Although it is the battlefield painkiller of choice, how commonly it is used in front-line first aid isn’t known.

PTSD is characterized by intrusive thoughts and memories, a desire to avoid specific situations or stimuli, and feelings of both numbness and extreme vigilance. The disorder is common in veterans of the Iraq and Afghanistan wars although its exact prevalence is also uncertain.

About 40 percent of those veterans cared for at Department of Veterans Affairs hospitals have PTSD. Repeat deployment to a war zone increases a soldier’s risk of developing of the disorder. PTSD can also come on slowly. In one study, 4 percent of soldiers had the condition; six months later the prevalence was 12 percent.

In the new study, Holbrook and her colleagues studied the records of 696 wounded people. About 40 percent had been injured by “improvised explosive devices” — generally roadside bombs, and about 20 percent by gunshots, and 10 percent by mortar rounds. Roughly 70 percent of the people received morphine within an hour of injury.

Most people developed PTSD, diagnosed from one month to two years after their injuries. Those who’d gotten morphine, however, were somewhat less likely. Sixty-one percent had the disorder, compared to 76 percent of people who hadn’t gotten the drug — a 53-percent reduction in risk.