Researcher studies cause of disorder
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By Gordon Dritschilo Staff Writer - Published: May 25, 2008
When most of us think of the night sky, we think of stars.
Combat veterans with post-traumatic stress disorder, however, associate the heavens with a war zone. They picture incendiary rounds known as tracers.
That association appears to be physically embedded in the brains of PTSD sufferers, according to Dr. Matthew Kimble, an assistant professor in psychology and neuroscience at Middlebury College. Kimble is working with two undergraduates to measure the brainwave responses of people with PTSD to different stimuli using an EEG, or electroencephalograph.
The tests show fundamental biological differences in people with PTSD, Kimble said, negating the possibility that the disorder is faked.
"The bottom line is this whenever we learn something or experience something, your brain changes," he said. "When people experience traumatic events, their brains are changing, too. Ultimately, somewhere down the line, we'll be able to know what these changes are and measure them substantively."
Kimble's research, which is funded by the Vermont Genetics Network, part of the National Institute of Health, may have important implications not only for survivors of trauma but also for combat veterans. According to a Rand study corporation study published this year, 300,000 veterans one out of five who have returned from Iraq and Afghanistan, have been diagnosed with PTSD.
According to the National Institute of Mental Health, PTSD is an anxiety disorder that affects some people following a traumatic experience. Symptoms may include startling easily, irritability, aggression, difficulty feeling affectionate, and reliving the traumatic experience in thoughts and dreams.
Dr. Andrew Pomerantz, chief of mental health services at the Veterans Affairs hospital in White River Junction, said he sees a lot of PTSD patients.
"There are approximately 1,400 veterans receiving mental health care over the last year with PTSD as at least one of their mental health problems," he said.
About one-third of the VA's population has been consistently diagnosed with the disorder over the years, according to Pomerantz, though it often appears alongside other disorders. The age spread ranges from 18-year-olds to patients in their 90s.
"A lot has to do with what epoch they were in," he said. "We have a lot of people in that 50 to 60 age range who were in combat in Vietnam, also, a lot of people in the 70 to 90 range who were in Korea and World War II."
In recent years, Pomerantz said the VA has started seeing a number of patients in their 20s and 30s.
"It affects them in all domains of their functioning. It affects their personal life, how they sleep, how they think, how they interact with the rest of the world, how at peace they are with themselves," he said. "It just ripples all the way through everything they do."
PTSD affects the general population as well. Vermont Department of Mental Health statistics show 2,280 diagnoses of PTSD among community mental health service recipients in 2007. More than a third of those were children under 18.
"The problem with PTSD is it's often undiagnosed and often misdiagnosed as depression," said Sherry Burnette, the trauma coordinator for the Department of Mental Health.
Its causes stem from a variety of vulnerabilities and environmental stresses, according to Kimble.
"What's apparent from the statistics is while 90 percent of the American population will have had a traumatic event in the course of their adult life a motor vehicle accident, physical assault, sexual assault thankfully, 50 percent of the population does not have PTSD," he said.
Kimble said that studies of prisoners of war held at the infamous Hanoi Hilton in Vietnam, for example, showed an incidence of the disorder well below what researchers expected and that studies of Navy SEALs special forces famous for their grueling training have shown the commandos to be an incredibly resistant population.
Other people have a high vulnerability, Kimble said, and most fall between these two extremes.
The question is, why do some people develop PTSD?
"Certain individuals, for whatever reason the way their biology is, the way their brain is they develop PTSD-like symptoms," he said.
In search of
a cause and a cure
Pomerantz said there are a number of different treatment options. The most successful, he said, appears to be cognitive behavioral therapy. Medication, too, can help keep symptoms under control. Often, Pomerantz said, caregivers wind up describing options to patients and having them pick one.
"The real difficulty is in picking which treatment for which person," he said. "We don't have a way to do that effectively."
Pomerantz said much more PTSD research has been conducted in the last 10 to 20 years than ever before. He attributes this interest to an outbreak of symptoms among rescue workers and citizens of New York City following 9/11.
Kimble said he worked with 17 veterans and 16 civilians who had experienced some sort of traumatic event among them paramedics, assault victims and survivors of child abuse or car crashes.
"I think there was one individual, a college student, who had been close to Ground Zero on 9/11," he said.
The control group for the study consisted of people who had experienced trauma but did not exhibit PTSD symptoms. Trauma is defined as an experience involving a threat to your life or the life of someone you care about or a threat to your "physical integrity," such as rape or torture, to which you respond with intense fear, helplessness or horror.
The first of Kimble's undergraduates, Yanik Bababekov, measured the brainwave response to sounds. Bababekov, a senior from Boston, had his subjects listen to three tones. One similar to those used in hearing tests, another was a bell, whistle or clank, the third was like the first, only higher-pitched.
Bababekov said he could see how quickly the subjects paid attention to the tones and how much attention they paid by the nature of the brave waves. Bababekov said PTSD has been associated with attention deficits.
"What you'd expect to find is people with attentional deficiencies are going to show less cognitive resources," he said. "I actually found that neither PTSD nor dissociation nor depression were major contributors."
Earlier studies that associated attention deficit issues with PTSD focused on Vietnam veterans in their 60s, Kimble said. These subjects had been living with symptoms and taking medication for a long time. The Middlebury sample, he said, was younger and more diverse.
"There's a notion that people with PTSD are debilitated and can't do anything," Kimble said. "We've found a set of people with PTSD whose brains were normal."
At the same time, Kimble said, they found some significant differences.
Libby Marks, a senior from Ithaca, N.Y., tested how the subjects expected certain sentences to end. The researchers came up with 21 sentences, and then created three versions of each by changing the final word.
The first version was an expected conclusion: "The night sky was full of stars." The second was a confusing, often nonsensical conclusion: "The night sky was full of mushrooms." The third had a trauma-related conclusion: "The night sky was full of tracers."
Subjects were shown a series of sentences, one word at a time. The sentences were presented in a scrambled order so that versions of the same sentence did not necessarily follow one another.
The EEG indicates whether the conclusion to the sentence was what the subjects expected based on their brainwaves at the conclusion of each sentence. The results showed that those with PTSD were more expectant of the traumatic results.
Kimble said this built on earlier research that asked subjects to fill in blanks for the final word. That study, he said, found that PTSD patients were more likely to choose "chest" over "wallet" to complete the sentence "The man had a hole in his
"
Even though the terms used for the traumatic statements were generally related to the military or war, Kimble said veterans without PTSD were still much more likely to say the man had a hole in his wallet or that the night sky was full of stars.
Kimble said it is common for combat veterans to say they are always looking over their shoulders or sitting with their backs to the wall.
"Hypervigilant is the technical term," he said. "These guys are at home and they're safe but they walk a perimeter at night, checking all the windows, checking all the doors.
I think one of the things Libby's study demonstrated is that even in a population that's relatively normal as Yanik's study demonstrated these people are looking out for bad things to happen."
A possible criticism of that study, Kimble said, is that the subjects could have purposefully chosen answers they felt were appropriate to having PTSD. A brainwave scanner, he said, can't be fooled.
"It's the PTSD symptoms that are causing these reactions," he said. "These symptoms really and truly cause cognitive changes. These people may have experienced different traumas, but regardless of whether the stimuli are specific to their trauma, they react to them."
However, Kimble said the EEG is a long way from being suitable to test for PTSD, pointing out that the differences are group averages and do not apply universally to all people with PTSD.
"I think our most advanced understanding of PTSD is that it's consistent with other models of mental illness," Kimble said.
The study has no immediate implications for treating the disorder, Kimble said, but joins a growing body of knowledge which, taken as a whole, should help doctors address PTSD patients.
The study will continue next year, Kimble said, looking at the disorder from new angles, and with help from Norwich University. Kimble said he is still looking for test subjects, and interested persons should contact him at mkimble@middlebury.edu.
Contact Gordon Dritschilo at gordon.dritschilo@rutlandherald.com.
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