With American troops at war for more than a decade, an unprecedented number of studies are looking into war zone psychology.
And clinicians suspect that some troops are suffering from an emotional problem they call "moral injuries" — wounds from having done something, or failed to stop something, that violates their moral code.
A moral injury tortures the conscience. Its symptoms include deep shame, guilt and rage.
A former psychiatry consultant to the Army surgeon general, retired Col. Elspeth Ritchie, says it's not clear how to treat moral injury.
The Defense Department has approved funding for a study among Marines at California's Camp Pendleton to test a therapy that doctors hope will ease guilt.
But officials say a solution could be a long time off.
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