Activation of stress hormones like adrenaline in such situations stirs an animal or person to flight or fight. It also sharpens their memory. But, Pitman says, such a response sometimes "can be too much of a good thing. A process I call 'superconditioning' leads to the formation of a deeply engraved traumatic memory that subsequently manifests itself as the intrusive recollections and emotional responses of post-traumatic stress disorder."

Along with deliverance from death and disaster, you get a disorder. Propranolol shows a potential for curing that disease.

A widespread mental illness

According to a national study, about 8 percent of the U.S. population, some 20 million people, get PTSD sometime in their lives. It is the most important mental illness dogging the military. During the Vietnam War, about one of every three people involved in combat developed post-traumatic stress disorder. A surprising number of nurses who treated those soldiers, sailors, and Marines suffered from it, too. Pitman expects the same number of those who experience combat and terrorism in Iraq and Afghanistan to be PTSD casualties.

Giving propranolol to combatants in the field is not an idea that pleases generals, Pitman points out. Its anti-adrenal effect could block the will to fight along with easing heart palpitations and nightmares. But it could be given to those who are being evacuated, if medics have a good idea of who is most likely to suffer the disorder. Pitman's colleague, Scott Orr of Harvard Medical School, is doing experiments with firefighters and police officers to try to identify individuals who are most likely to be traumatized after experiencing intense stress.

That type of know-how would be helpful for people charged with the emergency care of civilians. In such cases, there is the additional problem of obtaining informed consent to administer drugs. Then there's the question of what is the best time to give such drugs. "There must be a critical window of time when PTSD drugs would be most effective," Pitman notes. "In the study at Mass General we gave propranolol within four hours of the trauma, maybe one hour would be better."

Finally, there's the ethical question. Leon Kass, chairman of the President's Council on Bioethics, objects to propranolol's use on the grounds that it medicates away one's conscience. "It's the morning-after pill for just about anything that produces regret, remorse, pain, or guilt," he says.

Pitman, however, thinks that an effective PTSD drug would do a lot more good than harm.