For psychologist Alain Brunet, the case is still astonishing. When Patrick Moreau first came into his office suffering from post-traumatic stress disorder (PTSD), the Canadian soldier, who had served as a United Nations peacekeeper in Bosnia, could hardly bear to recount the details of the day he was taken hostage in 1993. The memory--of kneeling on the ground with his hands on his head, legs shaking, a stark line of trees across the sky--aroused crippling fear that felt as fresh as it had 15 years before. The glimpse of a particular tree line through his windshield was enough to bring the memory rushing back, giving him such violent shakes that he would have to pull off the road.

But six months after participating in Brunet's clinical trial, Moreau no longer meets the diagnostic criteria for PTSD. He still experiences some flashbacks, but they are less frequent and less intense. He can now talk calmly and openly about what happened. And all he did was take a blood-pressure drug after writing down the details of the traumatic experience.