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Lesley Stahl: Many of us would pay top dollar for a pill that would enhance our ability to remember, but we found a scientist who was far more excited about a pill that promises to do exactly the opposite. If there were something you could take after experiencing a painful or traumatic event that would permanently weaken your memory of what had just happened, would you take it? It's an idea that may not be so far off, and it has some critics alarmed— and some trauma victims filled with hope.

Beatriz Arguedas: I couldn't get my body to stop shaking hands. I was trembling, constantly trembling. And memories of it would just come back— reoccurring over and over and over.

Lesley Stahl: Beatriz Arguedas is a subway conductor. Last September 30th, she was driving her normal route on the red line in Boston when one of her worst fears came to pass.

Beatriz Arguedas: Upon entering one of the busiest stations, a man jumped in front of my train to commit suicide.

Man: Entering Park Street.

Lesley Stahl: You actually saw him jump?

Beatriz Arguedas: I saw him jump. We sort of made eye contact, and then I felt the thud from him hitting the train and then the crackling sound underneath the train. And then, of course, my heart starts thumping.

DR. ROGER PITMAN: She came into our emergency room afterwards— very upset, no physical injury— entirely a psychological trauma.

Lesley Stahl: Doctor Roger Pitman is a psychiatrist at Harvard Medical School who has studied and treated patients with post-traumatic stress disorder, or PTSD, for 25 years.

DR. ROGER PITMAN: They're caught up so much with this past event that it's constantly in their mind. They're living it over and over and over, it's happening again, and they just can't get involved in real life.

Lesley Stahl: When Beatriz arrived in the emergency room, Pitman enrolled her in an experimental study of a drug called propranolol, a medication commonly used for high blood pressure and unofficially for stage fright. Pitman thought it might do something almost magical— trick Beatriz's brain into making a weaker memory of the event she had just experienced. In the study that is still underway, half the subjects get propranolol, half get placebo.

Do you know whether she got the drug?

DR. ROGER PITMAN: No idea.

Lesley Stahl: You have no idea?

DR. ROGER PITMAN: We have no idea, and she has no idea.

Lesley Stahl: To this day?

DR. ROGER PITMAN: We won't know for another two years.

Lesley Stahl: If Pitman is right, the results could fundamentally change the way accident victims, rape victims, even soldiers are treated after they experienced trauma. The story begins with some surprising discoveries about memory. It turns out our memories are sort of like jello— they take time to solidify in our brains. And while they're setting, it's possible to make them stronger or weaker. It all depends on the stress hormone adrenalin.

The man who discovered this is James McGaugh, a professor of neurobiology at the University of California, Irvine. McGaugh studies memory in rats, and he invited us to watch the making of a rat memory. In this case, how a rat— who's never been in this tank of water before— learns how to find a clear plastic platform just below the surface.

James Mcgaugh: He'll swim around randomly.

Lesley Stahl: Can he not see the platform?

James Mcgaugh: No, he can't see the platform. His eyes are on the top of his head.

Lesley Stahl: The rat will swim around the edge for a long time until eventually, he ventures out and by chance bumps into the platform. The next day, he'll find the platform a little bit faster. But watch this rat, who learned where the platform was yesterday then received a shot of adrenaline immediately afterward.

James Mcgaugh: Notice that it starts out not on the edge.

Lesley Stahl: Ooh.

James Mcgaugh: There you go.

Lesley Stahl: Oh, that's impressive.

Adrenaline actually made this rat's brain remember better. And McGaugh believes the same thing happens in people.

James Mcgaugh: Suppose I said to you, you know, I've watched your programs a lot over the years, and although it pains me to have to tell you this, I think you're one of the worst people I've ever seen on— now, don't take it— don't take it personally.

Lesley Stahl: So my stress system would go into overdrive, no question.

James Mcgaugh: Even with my telling you that it's not true, there's nothing to keep you from blushing— from feeling warm all over.

Lesley Stahl: I am warm all over.

James Mcgaugh: Yeah.

Lesley Stahl: I am. No joke. Really.

James Mcgaugh: That's the adrenalin. And I dare say that you're going to remember my having said that long after you've forgotten the other details of our discussion here. I guarantee it.

Lesley Stahl: The next step in his research was to see what would happen when adrenalin was blocked. He started experimenting with propranolol.

James Mcgaugh: Propranolol sits on that nerve cell and blocks it, so that— think of this as being a key, and this is a lock. The hole in the lock is blocked because of propranolol sitting there. So adrenalin can be present, but it can't do its job.

Lesley Stahl: Watch this rat, which just yesterday learned where the platform was, then received an injection of propranolol. Today, he just swims around the edge as if he's forgotten there ever was a platform out there.

Across the country at Harvard, Roger Pitman read McGaugh's studies and a light bulb went on.

DR. ROGER PITMAN: When I read about this, I said, this has got to be how post-traumatic stress disorder works. Because think about what happens to a person. First of all, they have a horribly traumatic event, and they have intense fear and helplessness. So that intense fear, helplessness is going to stimulate adrenalin. And then what do we find three months or six months or 20 years later? Excessively strong memories.

Lesley Stahl: Pittman figured he could block that cycle by giving trauma victims propranolol right away before adrenalin could make the memories too strong. He started recruiting patients for a small pilot study. One of the first was Kathleen Logue, a paralegal who had been knocked down in the middle of a busy Boston street by a bicyclist.

Kathleen Logue: He just hit the whole left side of my body, and it seems like forever that I was laying in the middle of State Street, downtown Boston.

Lesley Stahl: You must have been scared.

Lesley Stahl: Yeah, terrified that I was just going to get run over.

Kathleen Logue: Murray, Murray.

Lesley Stahl: As part of the study, Kathleen took propranolol four times a day for 10 days. Like the others who got the drug, three months later, she showed no physiological signs of PTSD while several subjects who got a placebo did. Those results got Pitman funding for a larger study by the National Institutes of Health. But then the President's Council on bioethics condemned the study in a report that said our memories make us who we are and that rewriting memories pharmacologically risks undermining our true identity.

This is a quote. "It risks making shameful acts seem less shameful or terrible acts less terrible than they really are."

Kathleen Logue: A terrible act— why should you have to live with it every day of your life? It doesn't erase the fact that it happened. It doesn't erase your memory of it. It makes it easier to remember and function.

Lesley Stahl: David Magnus, Director of Stanford University Center for Biomedical Ethics says he worries that it won't be just trauma victims trying to dull painful memories.

David Magnus: From the point of view of the pharmaceutical industry, they're going to have every interest in having as many people as possible diagnosed with this condition and have it used as broadly as possible. That's the reality of how drugs get introduced and utilized.

Lesley Stahl: He's concerned it'll be used for trivial reasons.

David Magnus: If I embarrass myself at a party Friday night, and instead of feeling bad about it, I can take a pill, then I'm going to— not have to avoid making a fool of myself at parties.

Lesley Stahl: So you think that embarrassment and all of that is teaching us.

David Magnus: Absolutely. Our breakups, our relationships— as painful as they are, we learn from some of those painful experiences. They make us better people.