By Rob Waters
A widely used heart drug may be able to stop frightening images or experiences from lodging in the memory and repeatedly resurfacing to cause fear and anxiety, researchers from the Netherlands reported.
A team at the University of Amsterdam gave the medication propranolol to test subjects in a complex experiment that measured how people reacted when they were shown pictures of spiders they’d been taught to fear. Propranolol is a so-called beta-blocker used to treat heart rhythm disturbances and high blood pressure.
The drug previously showed promise in a Harvard Medical School trial in preventing post-traumatic stress disorder, or PTSD, in people shortly after they’d had a car crash or been assaulted. Today’s results, published in the journal Nature Neuroscience, could provide a new way to treat thousands of combat soldiers and others who develop the debilitating symptoms of PTSD.
“The potential might be that we have a procedure that reduces irrational fears permanently,” said Merel Kindt, the University of Amsterdam psychologist who led the new findings. “This combination of giving the drug at the moment that you reactivate the memory, you disrupt the memory trace.”
People with PTSD are thrown into states of panic or anxiety when their memories of trauma are triggered by a sound, sight, or other experience that reminds them of their original trauma. The most common treatment for people with post-traumatic stress is an approach called exposure therapy. In that method, patients are helped to repeatedly relive the initial trauma in a safe setting until the emotional power of the memory dissipates.
The problem with this approach is that many people experience new shocks that throw them back into their original traumatized state of mind, said Kindt.
“You can experience a trigger that causes the fear to come back,” Kindt said in a Feb. 13 telephone interview. “If the emotional memory remains intact, it is very easy to recover that memory and thus the fear response.”
In the study, Kindt and her colleagues first conditioned their test subjects to fear a particular kind of spider by showing them pictures of the spider, followed by an electrical shock to the wrist.
One day later, the subjects came back. By then, the experience had been consolidated and stored in their memory.
Memory Faded, Reawakened
This time, some were given propranolol and others were given placebos before being shown spider pictures again -- with no electric shock. All the patients, including those who had taken propranolol, showed some fear of the pictures.
On the third day, when the placebo subjects were shown the spiders and given no shock, their fear response was high, while the propranalol users no longer showed fear. Then, just when they thought they were safe -- zap, they get shocked again. The people in the placebo group were thrown back into a state of fear and anxiety but there was no return of fear in the group that took the drug.
“This is a beautifully executed study,” said Roger Pitman, the Harvard psychiatry professor who led the earlier work on propranolol and wasn’t involved in these findings. “It suggests a real scientific basis for what we thought we observed in our study.”
Propranolol is most often prescribed to lower blood pressure and is marketed as a generic by Mylan Laboratories Inc. and by Wyeth as Inderal.
In Pitman’s earlier study of propranolol, patients came to a clinic for immediate therapy within a few hours of a traumatic event before the experienced was lodged in their long-term memory. Most people who experience trauma such as being shot at, or witnessing fellow soldiers get killed, can’t come to a clinic that soon.
“Unless they come in within 3 hours, that memory becomes consolidated,” Pitman said. “The problem with PTSD is the memory gets consolidated too strongly and becomes this durable memory that haunts people. Once a person has PTSD, it’s too late, the memory is written into the hard drive and the window of opportunity is closed.”
Kindt’s study suggests that intervention might still be possible later, Pitman said. The results suggest that with the drug, the active memory of their conditioned spider fear had been wiped off of their long-term memory, or at least was no longer accessible, he said.
Further research is needed to test Kindt’s approach. If it works, she said, it could replace exposure therapy. Instead, therapists would simply give patients propranolol at the same time that they trigger their memory of the trauma that’s plaguing them by briefly presenting them with an evocative sight or sound.
To contact the reporter on this story: Rob Waters in San Francisco at email@example.com