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by Kevin Hand

Clinical psychologist Alain Brunet of McGill University in Montreal doesn´t usually torture his patients. But lately he has been pressing those with post-traumatic stress disorder, or PTSD, to relive emotionally scarring incidents. For some it´s rape, others battlefield trauma. When his patients get particularly upset-crying, shaking, blood pressure rising-he gives them a 25-year-old hypertension drug called propranolol. The idea, though, is not to lower their blood pressure. Brunet´s goal is much more profound: to wipe away the trauma of bad memories.

Propranolol, it turns out, blocks the effects of stress hormones, which the body creates during traumatic â€fight or flight†situations. These hormones serve a critical function-namely, they help us survive life-threatening scenarios by sharpening our senses. But they can also permanently scorch traumatic sights, sounds and smells into the brain, creating a biochemical warehouse in which bad memories can live forever. For the estimated 1.9 million Americans suffering from PTSD, recalling a traumatic event can elicit the same panic response as the event itself.

Harvard University psychiatrist Roger Pitman has already published study results showing that patients given propranolol shortly after a traumatic event are significantly less emotional when recalling the experience. Now he and Brunet are taking the idea even further, attempting to deaden bad memories years after traumatic experiences. Their efforts build on groundbreaking research by Karim Nader, another McGill scientist, whose 2000 studies in rats showed that memories don´t become completely fixed in the brain, as was previously thought. Instead, when memories are recalled, they temporarily transfer back to short-term storage, where they can be more easily â€edited.â€

Brunet´s hope is that the drug will subdue the patient´s stress response and soften his or her perception of the traumatic memory [see illustration], thereby helping the patient create a new memory of the event-one without all the emotional baggage. So the next time the patient recalls the trauma, the memory of it will no longer cause panic.

In the past few months, Brunet has treated about 20 patients with the new method. â€So far, we´re encouraged by what we´ve found,†he says. The implications of his work are tantalizing, if a tad unnerving: People could essentially pop a pill to lighten up the darkest moments of their lives.

How it Works:

  1. Trauma triggers the amygdala to release stress hormones, which enhance memory formation in the brain.
  2. Memories of the trauma are first stored in the hippocampus. Then a chemical reaction encodes them into neurons in the cerebral cortex, cementing them into long-term storage.
  3. When a victim recalls the trauma, the memory transfers back to the hippocampus, where it can trigger the release of more stress hormones.
  4. Propranolol blocks the effects of the hormones and softens the victim´s perception of the trauma. The brain restores the newly edited memory.

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