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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

Genes, Environment, and Trauma continued...

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.

Close proximity more than doubled the women’s risk for psychological problems in the weeks after the shooting.

Ressler then compared the women’s genotypes to their PTSD symptoms.

Those who inherited genes, including 5-HTTLPR, that made them slower to clear serotonin were more likely to go on develop symptoms of posttraumatic stress disorder than those who could clear serotonin more quickly.

That relationship remained even after researchers adjusted for the women’s exposure to the trauma, and Ressler says, a woman’s genes were nearly as powerful a predictor of future mental problems as how close she was to the violence.

“The really important thing about this study is that it shows that potentially, ordinary individuals will be able to take pre-emptive action to stop themselves from getting illnesses like PTSD and depression,” which can be chronic and disabling, Moffitt says.

One day, she says, genetic testing may educate people about their ability to withstand stress.

People who know what genes they carry, she says, “have the option to take action and seek support from friends, family, or a mental health professional, as soon as a major stressful life event enters their life.”

Other experts agree.

“The genetic factors, which we have always known seem to exist, this study gives some evidence to that,” says Alan Manevitz, a clinical psychiatrist at Lenox Hill Hospital in New York City who was has helped to treat survivors of the 9/11 attacks and Hurricane Katrina.

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