WASHINGTON, Nov. 25, 2008 — Most people's stress response system acts like a home heating thermostat: it responds appropriately to environmental cues, such as wind or snow, by kicking up the heat.
But after a life-threatening experience, some people's physiological thermostats recalibrate to a lower threshold. This heightened sensitivity is a hallmark symptom of post-traumatic stress disorder, an anxiety condition that manifests itself as a range of emotional and behavioral changes aimed at coping with
The disorder can be seen in the example of a servicemember who returns to the United States after surviving an attack from a roadside bomb hidden in a pile of garbage in Iraq. Even away from the combat zone, a pile of trash along the highway -- what others motorists might consider commonplace -- can trigger a fight-or-flight response in the afflicted troop.
"With PTSD, there is this stress response system that goes into overdrive in response to things in the environment that it has come to associate with being in danger, and it turns up the heat," said Dr. Farris K. Tuma, chief of the Traumatic Stress Research Program at the National Institute of Mental Health.
A study released in April found that nearly 20 percent of Iraq and Afghanistan veterans report PTSD symptoms. Though each servicemember displays a "constellation of differences," the common thread among those diagnosed is the daily impairment of normal functioning that lasts at least six weeks, said Tuma, who participates in several interagency work groups to help in coordinating research on PTSD across DoD, VA and NIMH.
In addition to elevated levels of arousal, also known as hypervigilance, other PTSD characteristics include the avoidance of reminders and re-experiencing the event, Tuma said. These symptoms can come in the form of persistent frightening thoughts and memories of their ordeal, emotional numbing, sleep problems or detachment from others.
Biologically, PTSD changes neuro-endocrine levels, primarily in two parts of the brain, experts believe. The first is the amygdale, an almond-shaped mass of grey matter located in the temporal lobes just above the ears, which regulates aggression and fear.
The other affected area is a section of the prefrontal cortex, which is believed to dictate responses of avoidance and numbing.
Using functional magnetic resonance imaging, or fMRI, Army Col. (Dr.) Michael J. Roy, a medical internist and director of Military Internal Medicine, and his staff are able to show evidence of PTSD's neural pathways. Doctors can detect what areas of the brain are engaged by monitoring levels of
"I show you a picture of war on the screen, and that stimulates a certain part of your brain, which uses more oxygen," Roy said. "Very briefly, for maybe a couple of seconds, you see a decrease of oxygen in those cells. People with PTSD seemed to have increased activation in the amygdale and less inhibition in the frontal lobe."
Though the understanding of PTSD's neural routes and its medical treatment have greatly evolved since it was initially diagnosed in 1980, the relationship between war and psychological trauma was documented as early as Ancient Greece. In his epic poem "The Iliad," Homer shows protagonist Achilles ruminating after hearing of the death of his closest companion, Patroclus.
"My comrade is dead, who in my hut is lying mangled by the sharp spear, with his feet toward the door, and round him our comrades mourn, wherefore in my heart to no thought of those matters," Achilles says, adding, "I will force my soul into subjection as I
The dialogue is a textbook portrayal of the type of numbing and other features associated with the disorder, Roy said.
"Achilles really didn't want to go back to war, because his friend died," he said. "All the kinds of symptoms he describes there are PTSD."
PTSD was first brought to public attention in relation to war veterans, but the disorder affects the civilian population in larger numbers than military personnel. It can result from a variety of traumatic incidents such as mugging, rape, torture, child abuse, a plane crash or a natural disaster, according to the National Institute of Mental Health Web site.
"It's an equal-opportunity offender," said Tuma, adding that car accidents are the No. 1 cause of PTSD. He noted that among the civilian population, members of law enforcement and firefighters are
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