All in Your Head

	The hippocampus, a region of the brain associated with memory, can be damaged by the prolonged release of stress hormones.

Faced with scores of traumatized veterans of the Viet Nam war, researchers have been studying the underlying physiology of PTSD since the late 1960s. Animal studies have shown repeatedly that prolonged stress releases hormones that can damage the hippocampus, a region of the brain associated with memory. In a series of brain imaging studies conducted with humans in the mid-1990s, researchers found that the hippocampi of PTSD sufferers were smaller than average. These findings lead some to hypothesize that the damage extreme stress does to the hippocampus causes PTSD; however, a study published in the October 2002 issue of Nature Neuroscience suggests otherwise.

Using MRI bran imaging, a group of Harvard Medical School researchers studied pairs of identical twins in which one twin served in Viet Nam and the other did not. As expected, the veterans with PTSD did in fact have smaller hippocampi than the veterans who did not. But when the researchers looked at the twins who did not serve in Viet Nam, they found the brothers of the veterans with PTSD also had smaller than average hippocampi. These findings suggest that a smaller than average hippocampus is not the result of PTSD, but a risk factor for developing it.

View Scientific American Frontiers segment about James McGaugh"s research, "Remembering What Matters"

Another area of the brain implicated in PTSD is the amygdala, which processes emotional memories. James McGaugh, a researcher at the University of California, Irvine, showed that the stress hormone adrenaline acts on the amygdala to enhance the learning process in rats. Working with human subjects, McGaugh also demonstrated that people remember a series of images better when they are told emotional details about them.

Moreover, McGaugh showed that he could block adrenaline's memory-enhancing effect on the amygdala with drugs called beta blockers. While they were told the emotional story, one group of people was given beta blockers while a control group was not. When tested later that day, all the people had heightened memories of the stories and images. But, when they were tested two weeks later, the people given the beta blockers had forgotten a great deal, while the memories were just as vivid for the control group. In 2002, several research groups announced plans to run human trials with adrenaline blocking drugs.

Treatment and Prevention

Currently, there is no surefire cure for PTSD. The National Institute of Mental Health lists cognitive-behavioral therapy and exposure therapy-in which patients repeatedly confront reminders of the event until it no longer affects them-as methods with proven track records. Anti-depressants are often prescribed to alleviate the disorders that often accompany PTSD, such as depression, anxiety or substance abuse.

In the wake of September 11th, 2001, researchers rushed to learn as much as possible about the psychological fall out of the terrorist attacks. Many of these studies are still underway and they cover topics ranging from tracking neurological changes in people who witnessed the attacks to examining how American's attitudes about race were affected. Researchers are also looking at prevalence and prevention of PTSD in first responders like EMT's and firemen and how to cut the economic costs PTSD.

For more information about PTSD and it's treatment, see our resources section.

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