Drug eases pain of bad memories for veterans with PTSD

Drug eases pain of bad memories for veterans with PTSD
by Peter Gorner, Chicago Tribune

CHICAGO – Armed with new information about how brain chemicals affect the storage and retrieval of memories, scientists are racing to help people tortured by searing recollections of traumatic events.

Military combat, rape, bombings, burns, beatings – these experiences can lead to post-traumatic stress disorder, in which the sufferer relives the event over and over to devastating effect, sometimes many years after the fact.

There is no definitive treatment for PTSD and no cure, and the number of cases is only expected to grow as a result of U.S. military action overseas. Last week, published research found that 12 percent of soldiers returning from Iraq were diagnosed with post-traumatic stress disorder, depression or another serious mental illness.

Brain scientists think they have found a way to help by using a drug called propranolol to alter traumatic thoughts. It appears that the drug, a beta blocker used to treat blood pressure, interferes with stress hormones in the brain to defuse the impact of horrific memories…

While use of the drug for this purpose has not been approved, some psychiatrists already have begun to prescribe it off-label to patients with PTSD. (Other beta blockers do not seem to affect the brain the same way.)

Researchers emphasize that the drug can lower the intensity of a bad memory – but not erase it. “It’s not that people will no longer remember the trauma, but the memory will be less painful,” said Alain Brunet, a psychologist at McGill University in Montreal, where experiments on human subjects are under way.

If the drug works on PTSD, experts say it also might help with drug addiction, stage fright, trembling, epilepsy and other conditions caused by changes in the brain’s wiring.

The idea that a drug could affect memory flies in the face of a century of scientific belief. The thinking was that memories exist in an unstable state only for a short time; after roughly six hours, they get “consolidated” and stay that way forever.

But Karim Nader, a pioneering McGill psychologist, was able to show that long-term memories aren’t nearly as hardwired as scientists had thought. When we retrieve a memory, Nader found, it again enters a vulnerable state where it could be manipulated or even lost.

“It was formerly thought that once a memory is fixed you can’t mess around with it,” said Nader. “That was scientific dogma for 100 years.”

The brain’s wiring changes each time something goes into long-term memory, but not all memories are equal, he said. “You remember the day of your wedding better than three Tuesdays ago when there was nothing important going on.”

Emotional memories, Nader explained, activate a second process that ups their intensity. This is called a “gain switch” and can be thought of as the volume control on a radio.

Studies have shown that emotionally arousing events cause stress-related hormones such as adrenaline to be released by the brain’s amygdala, which is involved in emotional learning and memory. PTSD may develop when the event is so emotionally powerful, and so much adrenaline is released, that the “gain switch” is set too high.

Then, each time the traumatic experience is recalled, the amygdala releases yet more hormones and intensifies the stressful memories even more.

“You can’t control the memory. It’s always invading your consciousness,” Nader said.

Propranolol throws a wrench into that self-perpetuating system by interfering with the amygdala’s receptors and ultimately allowing victims to maintain a level of memory similar to that of a bystander.

Nader and his colleagues have demonstrated this effect in rats. When the researchers reactivated a fearful memory in the rats – such as by putting them in a cage where they had previously been shocked – the animals who were given propranolol were no longer afraid.

Now the team is doing an experiment on men and women with post-traumatic stress disorder. The subjects are fitted with headphones so they can listen to recordings of their own vivid descriptions of traumatic events they went through.

Palm sweat, heart rate and other changes are measured to determine whether the physiological response to the traumatic story is less among those who took propranolol than among those given a placebo.

The study is not complete, but the researchers say they’re “encouraged and excited” with the early results.

“People with PTSD tell me their life is so miserable, they’re willing to try anything to feel better,” Brunet said. “I’m amazed that what seemed to be science fiction just a few years ago is being tested. So this is a really big move forward.”

Post-traumatic stress disorder has been an officially recognized illness since 1980. In the last five years, a total of 215,871 veterans received benefit payments for PTSD costing $4.3 billion, up from $1.7 billion in 1999, according to the Department of Veterans Affairs.

The disorder has been treated with varying success with antidepressants like Prozac, Paxil and Zoloft. Some psychotherapies – especially having patients repeatedly relive the frightening experiences under controlled conditions – seem promising and are being evaluated by the Institute of Medicine of the National Academies.

“But some people still can’t get the trauma out of their mind,” Nader said. “They sit at home, this overwhelms them, they’re incapacitated and they’re resistant to the traditional treatments. What are we going to do for these people?”

Dr. Roger Pitman, a professor of psychiatry at Harvard Medical School, wondered if giving propranolol as soon as possible after a traumatic event could prevent indelible, terrifying memories from taking hold.

He tested the idea on 41 people who had experienced car accidents, assaults and other events that brought them to a Massachusetts emergency room. They received the drug within six hours of their mishaps.

The results were dramatic. Three months later, 22 of the victims listened to audiotapes on which they had described their traumas. None of those who took propranolol showed strong responses to the tapes, but eight of the placebo patients were obviously shaken by reliving their experiences. Their heart rates increased, their palms sweated, their muscles twitched – all signs of PTSD.

Now Pitman’s group is pursuing a study in which patients with chronic PTSD are treated repeatedly with propanolol.

“If we get positive results, there are many potential applications for people with PTSD from a variety of sources, including Hurricane Katrina and the Iraq War,” Pitman said.

The scientists acknowledge that any treatment involving “therapeutic forgetting” is controversial. Some ethicists worry that such treatment may numb us and make us less capable of handing psychological pain. Others contend that random traumas and horrific memories of wartime combat serve no purpose and are best forgotten.

But the brain researchers emphasize that they are not trying to erase people’s memories.

“Many people have thought of these as amnesia drugs: `I would like to get rid of the memory of a horrible experience I had with another person; I’ll just take propranolol and get rid of it,'” said James McGaugh, a neurobiologist at the University of California at Irvine whose work on learning and memory paved the way for research by Pitman and others. “Well, propranolol does not remove memories.”

The day after Nader’s first study was published, a woman called and asked whether she could have the memories of her abusive first husband erased.

“The idea of erasing memory is just silly,” Nader said. “We can’t do it; nor do we want to. But if we can turn down the intensity of the memory sufficiently that these patients can respond to traditional treatments, that’s the goal, I think.”

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