Boston ? 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 today’s New England Journal of Medicine.

Whether the Pentagon will adopt the practice on the battlefield remains to be seen.