Pulse

Seeking to help soldiers trapped by the trauma

Researchers in Tampa hoping to help veterans suffering from Post-Traumatic Stress Disorder have proved for the first time that reliving the nightmares of combat cripples the ability to learn.

Results from the study at the University of South Florida and James A. Haley Veterans Hospital in Tampa were presented Sunday at the national Experimental Biology 2003 meeting in San Diego. Researchers hope that their discovery will lead to drug treatments that block the disturbing memories that haunt some soldiers and ravage their post-war lives.

"We may not be able to block the memory. But we may be able to allow the memory to function normally, to make it like any other bad memory" so it does not paralyze sufferers when it resurfaces, says behavioral neuroscientist Dr. David Diamond.

Post-Traumatic Stress Disorder is an anxiety reaction to a traumatic event replayed over and over. The sufferer has no control over the memories and the powerful physical and mental reactions they cause.

Diamond hopes that soldiers in Iraq will suffer less from the disorder because of public support for them. A lack of community when Vietnam vets returned home was a major factor in incidence of Post-Traumatic Stress Disorder from that war, he says.

In contrast, more cases could emerge from Iraq because of larger numbers of women soldiers, about 15,000, he estimates. Women are more susceptible to the disorder, Diamond says, perhaps because of differences in how they process trauma.

Diamond and his research partner, Dr. James Woodson, began studying "intrusive memories" two years ago.

They drafted rats to give them answers.

Rats' physiology is similar to humans, and the animals release the same chemicals when stressed, Diamond says.

For the experiment, a rat was placed in a small box divided into enclosed and open areas. Rats will typically seek a dark space to hide. In this box, the rat received a shock to a paw if it went into the enclosure. When placed in the box six months later, the rat, acting against instinct, avoided the enclosure, remembering its previous experience and remaining in the light.

In a rat, six months is one-fourth of its life span, or the equivalent of about 18 years in a human's life.

But the point of the research was not to show that rats remember. "What's important to us is that when people have traumatic memories, they are intrusive, pathological," Diamond says. "Would the rat not only remember, but would the memory intrude in its life?"

The rats were trained to find an exit from a 6-foot tank of water by remembering where a platform was hidden, like a human "remembering where he parked his car at the mall," Diamond says. The task is easy for rats, which have keen spatial ability, he says.

But when the rats were put in the box where they had once experienced the trauma of an electric shock, then put in the tank, they had "complete amnesia. They'd forgotten what they'd learned only 30 minutes earlier" about where to exit, Diamond says.

"Now they couldn't function because of the panic."

The rats' behavior shows that many years after a trauma has occurred, memories will interfere with what a person is attempting to learn at the time.

"We can help people if we can discover why," Diamond says. "In extreme Post-Traumatic Stress, the traumatic memory is so strong, it consumes someone. We have Vietnam vets and World War II vets who are impaired for decades."

Diamond and Woodson believe that although nightmarish memories cannot be blocked, they can be diminished. Tests are under way on a new drug to block the stress effect of such memories. Results are expected by November.

Post-Traumatic Stress Disorder is a chronic health problem because the trauma is relived over and over, brought on by triggers as innocuous as loud noises, odors, foods or environment. For example, panic ensues for many Vietnam vets when the humidity is high, Diamond says. Humid weather, like that experienced in Vietnam, triggers the fear, shock, racing pulse, clouded thinking and panic suffered overseas. "One cue for Iraqi veterans might prove to be dry weather," Diamond says.

Sufferers cannot reclaim the life they had or move forward, because they re-experience the past over and over, Diamond says.

"We're trying to break that cycle."

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