Between 4 percent and 5 percent of returning Iraqi veterans with combat experience suffer from post-traumatic stress disorder.

In both animal trials and preliminary work with humans, use of the beta blocker propranolol during a PTSD attack appeared to help separate the fear that's characteristic of PTSD from the memory that once triggered it.

The researchers don't think the beta blocker erases or diminishes the memory.

"Our expectation is that we're reducing the hyperarousal associated with the memory -- we expect that the memory will still be there," explained lead researcher Dr. Margaret Altemus, an associate professor of psychiatry at the Weill College of Medicine at Cornell University, in New York City.

Used to Desensitize?

But this new approach to easing PTSD symptoms isn't without its critics, one of whom worries the drug might be misused to desensitize individuals, such as soldiers, to acts of atrocity.

At this point in the research, though, it's too early to tell how well beta blockers might work even as a therapeutic aid, Altemus said.

"There were two small studies that have already been done using propranolol for PTSD, where they treated people right when the accident happened -- they found people in the emergency room. One study was done in France, and one was done in Boston," she said. "They did find they were able to reduce the [emotional] intensity of traumatic memories by giving people propranolol for the first 10 days or so after an accident."

But Altemus also pointed out that PTSD is rather rare, with less than 10 percent of accident victims experiencing the recurrent flashbacks, isolation and avoidant behaviors that are hallmarks of the condition. So, it wouldn't make sense to hand out propranolol to everyone who'd suffered a traumatic event, she said.

Lessens Fear Response

In theory, beta blockers such as propranolol work to reduce memory-associated fear through their effects on hormones linked to fear and arousal.

"Every time you have that intense, overwhelming fear in a PTSD attack you release catecholamines -- another word for adrenalin hormones," Altemus explained. "Those actually make the memory stronger and more intense. So, it's a kind of vicious circle for people with PTSD."

"What propranolol does is block one of the [cell] receptors that catecholamines work on, the beta-adrenergic receptor," she added. The theory is that by blocking this hormonal response during memory-evoked PTSD attacks, individuals will gradually be able to remember the triggering event without its attendant panic and fear.

In animal studies, Altemus' team found that mice trained to fear a tone followed by an electric shock lost that fear if given propranolol just after the tone started.

The researchers have also done work in healthy, non-PTSD individuals, conditioned in the lab to fear seeing a blue square because it had previously been linked to a mild electric shock.

"In our preliminary analysis that we presented at the Society of Neuroscience meeting last year, we did see that -- at least initially -- people that took propranolol had less of a fear response [to the square] on the third day. That work hasn't been published yet, but it's encouraging," Altemus said.

Exposure Therapy Effective

Beta blockers are not the first drugs to be used in the treatment of PTSD; the US Food and Drug Administration long ago approved selective serotonin reuptake inhibitors (SSRIs), such as Paxil and Zoloft, for the condition.

But the most effective and widely used treatment by far is "exposure therapy" -- where the patient is exposed to stimuli associated with the traumatic event. Altemus said many patients would welcome a treatment option that allowed them to avoid that type of re-living of the experience, however.

She stressed that beta blockers, if proven effective, "could be used to augment other therapies. It might be something you could add to exposure therapy, to help it work better," she said. The drugs have few side effects, but they are not recommended for individuals with either asthma or diabetes, the researcher added.

Going 'Where Angels Fear to Tread'?

However, one expert is concerned the drugs might have a darker side. In an interview with Nature magazine this week, Dr. Paul McHugh, a psychiatrist at Johns Hopkins University in Baltimore, worried that, "If soldiers did something that ended up with children getting killed, do you want to give them beta blockers so that they can do it again?"

McHugh, who is also a member of the President's Council on Bioethics, believes "psychiatrists are once again marching where angels fear to tread."

But Altemus believes McHugh is looking at trauma's aftermath in the wrong way.

"I think Dr. McHugh may have been assuming that what prevents soldiers from committing atrocities is this overwhelming fear," she said. "I've never been in a war, but my guess is that they do these things because they are really angry, or through some kind of group attitude."

Altemus also believes that effective PTSD treatments might "unlock" individuals otherwise emotionally frozen by traumatic events. "If you take someone who has been in the Holocaust or was raped -- their ability to change laws or prevent that event from happening again is actually inhibited by having PTSD," she said. "PTSD is a really disabling illness, and people are able to be themselves and be more active if they don't have it."

Returning Iraqi Vets

According to the Associated Press, a study released Thursday by the US Army surgeon general's office estimates that between 4 percent and 5 percent of returning Iraqi veterans with combat experience suffer from PTSD.

Funded by a grant from the National Institutes of Health, Altemus is currently working to recruit PTSD patients for a large-scale trial of propranolol -- a tough job when effective interventions such as exposure therapy already exist. She said that as soon as she's able to recruit the 60 people needed for the trial, results should be available within a year.

More information: For more on PTSD, head to the National Institute of Mental Health.