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    School Shooting Study Shows Genetic Links to PTSD

    Genes May Have Role in Determining Who Bounces Back, Who Struggles After Trauma

    Violence and Opportunity continued...

    “What these very clever scientists have done is they have essentially carried out what is tantamount to a natural experiment,” says Caspi, who with his research partner at Duke, Terrie Moffitt, PhD, first showed that genes could influence the development of depression after stressful experiences.

    They were not involved in the current study.

    “By capitalizing on the fact that they had data before, there’s a terrible event happening, and following up with these people after,” the researchers had produced very “strong and compelling evidence” of a genetic influence on the development of posttraumatic stress disorder (PTSD), he says.

    Genes, Environment, and Trauma

    Two years later, Orcutt reached out to Kerry Ressler, MD, PhD, an associate professor at Emory University in Atlanta and an investigator at the Howard Hughes Medical Institute in Chevy Chase, Md., who is working to identify genes that predispose people to developing PTSD.

    He analyzed DNA samples from more than 200 women in Orcutt’s study who were free of any symptoms of PTSD before the shooting.

    He was looking for differences in genes that make a protein that clears the mood chemical serotonin from the spaces between nerve cells in the brain.

    This protein, the serotonin transporter protein, and the genes that determine how it works are some of the most important biomarkers in modern psychiatry. Drugs that block the function of the serotonin transporter protein, for example, Prozac and Zoloft, are used to treat depression.

    And last year, researchers at the University of Michigan found that incoming medical students with the 5-HTTLPR gene variant, which means they make less serotonin transporter protein, were also more likely to develop depression by the time they were ready to take their exams.

    Ressler wanted to see if the same gene variants might be linked to how well the women at Northern Illinois University had coped with their experience.

    As expected, those who were closest to the shooting -- they were in the lecture hall during the shooting, heard gunfire, saw the gunman, or were hurt -- were more likely to develop symptoms of PTSD than those who were more removed from the violence.

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