A pill to fade traumatic memories? Doctors are working on it
Monday, January 16th 2006, 9:47 am
By: News On 6
Suppose you could erase bad memories from your mind. Suppose, as in a recent movie, your brain could be wiped clean of sad and traumatic thoughts.
That is science fiction. But real-world scientists are working on the next best thing. They have been testing a pill that, when given after a traumatic event like rape, may make the resulting memories less painful and intense.
Will it work? It is too soon to say. Still, it is not far-fetched to think that this drug someday might be passed out along with blankets and food at emergency shelters after disasters like the tsunami or Hurricane Katrina.
Psychiatrist Hilary Klein could have offered it to the man she treated at a St. Louis shelter over the Labor Day weekend. He had fled New Orleans and was so distraught over not knowing where his sisters were that others had to tell Klein his story.
``This man could not even give his name, he was in such distress. All he could do was cry,'' she said.
Such people often develop post-traumatic stress disorder, or PTSD, a problem first recognized in Vietnam War veterans. Only 14 percent to 24 percent of trauma victims experience long-term PTSD, but sufferers have flashbacks and physical symptoms that make them feel as if they are reliving the trauma years after it occurred.
Scientists think it happens because the brain goes haywire during and right after a strongly emotional event, pouring out stress hormones that help store these memories in a different way than normal ones are preserved.
Taking a drug to tamp down these chemicals might blunt memory formation and prevent PTSD, they theorize.
Some doctors have an even more ambitious goal: trying to cure PTSD. They are deliberately triggering very old bad memories and then giving the pill to deep-six them.
The first study to test this approach on 19 longtime PTSD sufferers has provided early encouraging results, Canadian and Harvard University researchers report.
``We figure we need to test about 10 more people until we've got solid evidence.'' said Alain Brunet, a psychologist at McGill University in Montreal who is leading the study.
It can't come too soon.
The need for better treatment grows daily as American troops return from Iraq and Afghanistan with wounded minds as well as bodies. One government survey found almost 1 in 6 showing symptoms of mental stress, including many with post-traumatic stress disorder. Disability payments related to the illness cost the government more than $4 billion a year.
The need is even greater in countries ravaged by many years of violence.
``I don't think there's yet in our country a sense of urgency about post-traumatic stress disorder'' but there should be, said James McGaugh, director of the Center for the Neurobiology of Learning and Memory at the University of California at Irvine.
He and a colleague, Larry Cahill, did experiments that changed how scientists view memory formation and suggested new ways to modify it.
Memories, painful or sweet, don't form instantly after an event but congeal over time. Like slowly hardening cement, there is a window of opportunity when they are shapable.
During stress, the body pours out adrenaline and other ``fight or flight'' hormones that help write memories into the ``hard drive'' of the brain, McGaugh and Cahill showed.
Propranolol can blunt this. It is in a class of drugs called beta blockers and is the one most able to cross the blood-brain barrier and get to where stress hormones are wreaking havoc. It already is widely used to treat high blood pressure and is being tested for stage fright.
Dr. Roger Pitman, a Harvard University psychiatrist, did a pilot study to see whether it could prevent symptoms of PTSD. He gave 10 days of either the drug or dummy pills to accident and rape victims who came to the Massachusetts General Hospital emergency room.
In follow-up visits three months later, the patients listened to tapes describing their traumatic events as researchers measured their heart rates, palm sweating and forehead muscle tension.
The eight who had taken propranolol had fewer stress symptoms than the 14 who received dummy pills, but the differences in the frequency of symptoms were so small they might have occurred by chance _ a problem with such tiny experiments.
Still, ``this was the first study to show that PTSD could be prevented,'' McGaugh said, and enough to convince the federal government to fund a larger one that Pitman is doing now.
Meanwhile, another study on assault and accident victims in France confirmed that propranolol might prevent PTSD symptoms.
One of those researchers, Brunet, now has teamed with Pitman on the boldest experiment yet _ trying to cure longtime PTSD sufferers.
``We are trying to reopen the window of opportunity to modulate the traumatic memory,'' Pitman said.
The experiments are being done in Montreal and involve people traumatized as long as 20 or 30 years ago by child abuse, sexual assault or a serious accident.
``It's amazing how a traumatic memory can remain very much alive. It doesn't behave like a regular memory. The memory doesn't decay,'' Brunet said.
To try to make it decay, researchers ask people to describe the trauma as vividly as they can, bringing on physical symptoms like racing hearts, then give them propranolol to blunt ``restorage'' of the memory. As much as three months later, the single dose appears to be preventing PTSD symptoms, Brunet said.
Joseph LeDoux, a neuroscience professor at New York University, is enrolling 20 to 30 people in a similar experiment and believes in the approach.
``Each time you retrieve a memory it must be restored,'' he said. ``When you activate a memory in the presence of a drug that prevents the restorage of the memory, the next day the memory is not as accessible.''
Not all share his enthusiasm, as McGaugh found when he was asked to brief the President's Council on Bioethics a few years ago.
``They didn't say anything at the time but later they went ballistic on it,'' he said.
Chairman Leon Kass contended that painful memories serve a purpose and are part of the human experience.
McGaugh says that's preposterous when it comes to trauma like war. If a soldier is physically injured, ``you do everything you can to make him whole,'' but if he says he is upset ``they say, 'suck it up _ that's the normal thing,''' he complained.
Propranolol couldn't be given to soldiers in battle because it would curb survival instincts.
``They need to be able to run and to fight,'' Pitman said. ``But if you could take them behind the lines for a couple of days, then you could give it to them after a traumatic event,'' or before they're sent home, he said.
Some critics suggest that rape victims would be less able to testify against attackers if their memories were blunted, or at least that defense attorneys would argue that.
``Medical concerns trump legal concerns. I wouldn't withhold an effective treatment from somebody because of the possibility they may have to go to court a year later and their testimony be challenged. We wouldn't do that in any other area of medicine,'' Pitman said. ``The important thing to know about this drug is it doesn't put a hole in their memory. It doesn't create amnesia.''
Practical matters may limit propranolol's usefulness. It must be given within a day or two of trauma to prevent PTSD.
How long any benefits from the drug will last is another issue. McGaugh said some animal research suggests that memory eventually recovers after being squelched for a while by the drug.
Overtreatment also is a concern. Because more than three-quarters of trauma victims don't have long-term problems, most don't need medication.
But LeDoux sees little risk in propranolol.
``It's a pretty harmless drug,'' he said. ``If you could give them one or two pills that could prevent PTSD, that would be a pretty good thing.''
Klein, the Saint Louis University psychiatrist, said it would be great to have something besides sleep aids, antidepressants and counseling to offer traumatized people, but she remains skeptical about how much long-term good propranolol can do.
``If there were a pill to reduce the intensity of symptoms, that would be a relief,'' she said. ``But that's a far step from being able to prevent the development of PTSD.''
Only more study will tell whether that is truly possible.