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Getting closer to understanding post-traumatic stress disorder

A neurotransmitter that affects mood and mental function may determine who is more inclined to developing Acute Stress Disorder and then PTSD symptoms after a traumatic experience

New research that analyzed the genetics of students on a college campus where an active shooter killed 5 people (plus himself) and injured 21 may help in eventually predicting which individuals are most susceptible to Acute Stress Disorder, which is a precursor to PTSD.

The subjects studied were 204 young female undergraduates (mean age 20 years), most of them white and about half of them freshmen, at Northern Illinois University where a lone gunman went on a lecture hall shooting rampage on Valentine's Day 2008. Their exposure to the incident ranged from merely being on campus that day to seeing the gunman firsthand, although none was actually targeted by him.

Conveniently for the researchers, the women were already participating in an ongoing trauma study at the time of the sudden shared event. The researchers report a couple of interesting secondary findings.  

Not surprisingly, proximity mattered. Those who were in the building where the shootings occurred or were close enough to hear gunfire and see the attacker firing were "significantly associated" with severe stress symptoms.

But the predominant difference between those who suffered persistent serious stress effects and those who did not was genetic. DNA testing revealed that the students with particular variants related to the regulation of serotonin, a neurotransmitter that affects mood and mental function, may be predisposed to developing Acute Stress Disorder and then PTSD symptoms after a traumatic experience.

Specifically, these variants are referred to as "the 5-HTTLPR multimarker and rs25531 genotypes of the serotonin transporter gene." Interestingly, another genetic variant that has been linked with psychosis and suicide did not appear to be associated with PTSD symptoms.

Only a minority of people exposed to traumatic or life-threatening incidents develop PTSD. "One of the critical questions surrounding PTSD is why some individuals are at risk for developing the disorder...while others appear to be relatively resilient," the researchers write in a report of the study.

The new findings, they say, will help unravel the exact mechanism involved in the genetic association and may eventually help in predicting the individual risk for PTSD symptoms in the weeks and months after a traumatic event.

More work with the study group is anticipated.